Are you sure about that? I can't watch the episode at the moment to check, but as I recall, we only ever saw weapons fire hitting the Hammond's shield and there's nothing in the dialogue indicating otherwise. You can scroll through the screengrabs of the battle here:
Originally Posted by Rohan
This is the first instance of weapons fire hitting the Hammond:
This isn't definitive, as there are gaps in the screengrabs, but it's the best I can do to fact check this at the moment.
Rodney was given access:
I'm not even sure turning off their attack program was that difficult as noted by Rodney in the episode 'Progeny' when he easily found a way to remove the aggression program with a flip of a switch.
SHEPPARD: Niam gave you access to the program code, and you're screwing around with it.
The problem isn't changing the code, it's gaining access by hacking your way through Ancient security measures.
Later, in "Lifeline," Rodney gained backdoor access by using Elizabeth's connection to the collective and was able to activate their Wraith kill command. However, once that access point was severed, he was never able to get back into the system even though he spent months collaborating with Todd to try to get the Wraith virus to work:
McKAY: Ellis is gonna love this. I don't get it. We tried re-configuring your stand-down code; we tried programming the nanites to turn themselves off. Something should've worked.
WRAITH: They are a very complex and ingenious design.
McKAY: Yeah, well, I thought I was ingeniouser.
I think the problem is less finding the data and more understanding it. The Ancient database would be filled with mathematics and terminology that would would be very difficult for a third-party to understand. Especially if they're much less advanced. In "Tao of Rodney," McKay invented a whole new math in his mentally advanced state that he couldn't understand once he returned to normal. However, before that happened, he was able to figure out how to maximize Z.P.M. power, miniaturize a hyperspace engine for use in a jumper, etc. In O'neill's case, the repositories similarly evolved him mentally, but they also provided him with a framework to understand what's in the database.
But my problem is that Janus could has easily sectioned off a part of the Ancients database concerning specific data in the construction of ZPMs or drone weapons.
In "The Siege, Part 1," Weir stated that they were able to choose between the data they were able to save:
WEIR: How do I choose between Zero Point Module research and their work on ascension? Between weapons schematics and their notes on space travel? No matter what we choose here, invaluable information's gonna be lost, and that is just the information that we've deciphered. Now we all know we have barely even begun to scratch the surface. What if we destroy the cure for all disease, or even some piece of information that could lead to the downfall of the Wraith?
Earth's problem, and likely the Asgard's to a lesser extent, is that they simply do not understand all the information available to them in the database. It's like giving technical information related to building a car to the greatest thinkers in Ancient Greece. Those are not step-by-step tutorials that explain the whole process in the simplest possible terms. Rather, they're written with the assumption that you have a baseline understanding of the mathematics and terms used. And even with that, all it's going to tell you is how to put together parts that have already been constructed.
Just creating the wiring is an incredibly complex endeavor for anyone attempting to do so from scratch. We're able to do that because we have the infrastructure for it, so the how basically amounts to putting metal through a machine and then having another machine coat it in rubber. For the Ancient Greeks to do the same, first they have to understand how to build that machine, which itself requires an understanding of other machines that build the components of the the first machine.
Look at how long it takes countries to successfully develop their own nuclear weapon programs. Many have gotten help from foreign scientists and/or gained access to foreign data, but developing the infrastructure necessary to do what the United States accomplished in the 1940s is still a very long and grueling process.
To replicate a ZPM, you not only better understand the math behind doing so, lest you end up blowing up an entire planet, but you need complex machinery and infrastructure. Creating an artificial pocket of subspace time requires a machine, the components of a ZPM that taps into that pocket and directs it safely requires at least one machine, possibly more, to construct, and then there's the equipment needed to create the ZPM's crystal shell. All of these machines are going to be incredibly complex, and they will require other machines to build those machines and other machines still to build the second tier of machines.
Having access to raw data is a very small part of the equation. They could cut a lot of corners with the help Asgard technology, but even that requires they understand exactly what they're directing the Asgard core to replicate and they simply don't. They're not advanced enough mentally to be able to properly grasp all facets of Ancient science, and they don't understand the "language" behind Ancient data.
They definitely attacked them after the Ancients left...
We know that the Wraith turned them off. However it probably happened after the Ancients left as the timeline here gets a little iffy.
WRAITH: Many thousands of years ago. We had defeated the Ancients -- the galaxy was ours, and then these things appeared.
What's not clear is how long they waited to attack the Wraith after the Ancient's returned to Earth. "And then," in the context of something that happened 10,000 years ago, is could it happend a year after or a hundred years after.
I'm sure they could reactive their Wraith attack command as well. What I was trying to say was that if the Ancients used the Asurans as a weapon before they left (which they did not), then knowing that the Ancients could simply reactivate that attack code would have necessitated a different strategy on the part of the Wraith. Specifically, it would've meant they had to try to employ a more complicated virus that would not just alter Asuran programming, but also lock the Ancients out so they couldn't make changes without hacking their way through the Wraith's block. And since the Ancients are still around, in this hypothetical, the Wraith would be motivated to try to reprogram the Asurans to attack the Ancients, rather than to just shutoff their Wraith attack code. Depending on how weak ther Ancients were at the time, they may not have the ability to get around the lockout before overwhelmed by the Asurans.
If Rodeny could easily turn it back on then I'd imagine the Ancients would be able too.
The Wraith left a lot of Ancient technology behind simply because it wasn't worth the effort to bother with. They could have come down on the Ancient city from "The Tower" in force, but it wasn't worth it to them to lose the number of ships they would have had to in order to claim a few villages worth of people or destroy the technology for good. They get aggressive when someone has the ability to actively attack, as the Satedeans tried to do, but when the threat is a passive one, they mostly leave it alone. Some Wraith will test those defenses from time to time, but failure doesn't prompt the Wraith to rally an attack.
the Wraith were very thorough in destroying all their technology as it was the only thing that could compete against them. So I'd imagine they would have known about Asuras.
That, though, is different than the issue of Asuras. I do think they would seek to finish off the Asurans if they could, which is part of why I'm not so sure the Wraith ever knew where they came from. The other part is that I don't see how the Wraith could learn about the location of Asuras. The Wraith can't track enemy ships, the Ancients didn't include information about their nanite experiments on that planet in their database, the replicators can't be captured and made to be told where they're from, and there's nothing to indicate that their virus (or a separate virus) relayed information back to them.
Janus was the only one to help because he was the only one okay with time travel being used to manipulate the timeline. The council refused to do anything, not because they were entirely unsympathetic to the plight of the expedition or because they were against the idea of humans taking over the city, but because they were trying to limit her impact on a future they believed they had no right to know about, let alone change.
Only Janus helped to make sure Atlantis would survive. ... But at the very least leave behind detailed instructions with things they would need for the city to continue on after hearing Weir's story.
To the council: If Atlantis was meant to be found by humans and saved from destruction before it ran of power, so be it. The same applies if the city was meant to be found by humans and destroyed shortly after their arrival or if it was meant to be discovered by the Wraith and used as a means to conquer the Milky Way. This doesn't mean they don't have a preference between these possibilities. It just means that they don't believe they have a right to use technology to try to change the timeline in any way. Otherwise, they wouldn't have been trying to help ensure the city survived when the expedition survived; they would have been trying to use the jumper to stop the Wraith so that their people didn't have to flee.
There's no way to know what the consequences of trying to avoid a specific event would be. Helping Weir save the city could have led to it being captured by the Wraith and used to reach the Milky Way for all they knew.
Mind you, there's nuance involved. Moros was the strongest in favor of limiting the fallout from Weir being in the past. He was willing to bring Weir back to Earth with them, which would have impacted by the timeline further, but he really had no choice other than to kill her or to try to repair the time machine and use it to send her back. Melia was the bridge between Janus and Moros; like Moros she was concerned about the impact Weir's presence had on the timeline ("Let us hope Doctor Weir's arrival has not altered this eventuality. By directly encountering the Wraith, she may have already set in motion a chain of events that could lead to a future far different from the one she left."), but she was also sympathetic to Weir's plight and offered to block the Stargate. Right after she refused, Janus gave a little speech to try to convince her they should do more to help, and Melia paused, looked like she was torn, and then said the council's decision was final.
Melia offered to lock out Earth's gate from dialing Atlantis. So there only issue was traveling through time and not changing events.
There's nothing to indicate Moros or the council at large would have agreed to blocking the Stargate.