I'd assume the Jays would get Bradley+cash in that deal. Either way, seems like a fine deal, and the Mets could then sign Orlando Hudson to play 2B - although it's not like he's that great of a player anymore. Hell, Castillo probably was a tad better than Hudson last year.
I'm not a huge Overbay fan, but I'm not expecting all that much in return for Castillo anyways. I suppose he would make a fine one-year stop gap at 1B until Ike Davis is ready, but I'd rather give Murphy a shot though personally. Who knows, maybe Murphy won't be here next year either.
As for 2B, while I suspect it'd be Orlando Hudson (Who by the way still had 40 points in OPS on Castillo and better D, albeit still a concern), I'm rooting for Felipe Lopez personally. Either way, keep it to a 2 year deal max.
Figgins is a career .751 OPS hitter, who you guys want to plug into LF (A position he has never played well, and has much higher offensive expectations then his current position does). Gardner on the other hand, we know can play a Great OF, and put up a .724 OPS (In essentially his rookie year) last year with comperable speed in limited playing time.
I'm not saying he's a bad player, but that's not who the Yankees should be going after. They'd be better off giving Gardner a larger role if Speed is what they're trying to obtain.
And the Mets need Power, so he's not a fit there either.