If Maria remains focused throughout the entire match, then she shouldn't have too much trouble, especially if she's feeling confident with her two straightforward wins this week. If she lapses for 10-15 minutes, then she can be in trouble in a set or even lose one, but either way I don't see Maria losing this match. I predict 6-4 6-3 or 6-3 7-5.
Tough to call. I feel Kerber is playing more passively and not going for as many winners when she gets the opportunity as she was when she beat Maria in Paris -- and, contrary to popular belief, you can't beat Maria in good form by purely Wozniacki-like defending, you need to properly counterpunch and turn defence into attack and not give her a chance to stay in the point. BUT, whether Maria is actually in good form remains to be seen, and if she's as ragged and unfocussed as she was in Tokyo last week, even Kerber playing pure defence will probably be able to beat her.
Going with Maria to win 2-6 6-4 6-3 or something like that.