A: Play All is not like an Action card which needs to be resolved before considering win conditions. It is “resolved” by changing the rules of the game. You play it, the rules change, and it’s done. Now it’s just in effect. After that Andy is just taking his turn, following the current rules, playing each card, and considering, after each play, whether he’s met the win conditions.
If you’re asking whether he can win in the middle of his turn, the answer is simply: yes. After all, he could win in the middle of someone else’s turn, too, if the cards play out right.