That was a good episode. Poor Alex... her boyfriend and long lost mom getting shot before her eyes. It was a good call for her to stand up and say she's Ben's daughter since whoever it is that was shooting, they'd want her for something.
I don't think this episode disproves that Michael isn't one of the 6. He's technically back at the island, if not on it yet, and he could have re-escaped with the other 5.
Writing Walt out was inevitable. The show has been on for 4 years, but only what, 3 months have passed on the island? It's kinda hard to pass a 14 year old off as a 10 year old, especially since I'm sure the actor was older than 10 when he was cast.
I hate waiting!!