Actually, strange as it may seem, I have the feeling this is more Microsoft's doing than Nintendo's. Microsoft were quite clear when they bought Mojang that it's going to remain a separate company and not be integrated into the Xbox division, and in that position MS is going to want Mojang to be as profitable as possible, which basically means porting Minecraft to every platform going. The XBox360/PS3 editions were the result of the platform holders themselves pushing heavily for the ports (and likely paying for them too), and there's no indication Notch had any intention of bringing the game to anything other than PC and possibly mobile (hence why the ports are handled by a different studio). It seems that Nintendo never pushed for a Wii U port, but now that Mojang is owned by a company which is firmly focussed on profitability they don't have to push.
Unlikely.
Assuming this port is the game being handled by Tantalus/Straight Right (highly likely),then it was confirmed for production way back in January 2014...so it was signed and sealed months before Microsoft acquired Mojang.