If it's not too expensive an extra I don't see why not.
5jiggahertz will probably be more loved with n's successor.
Wii U uses n, but I'm not sure if it's mimo or whatever it's called where it uses both to make it full duplex.
I think the upad uses 5, but not sure and won't have anything to do with your router.
True, 802.11ac runs purely on 5GHz. I believe it does support mimo, but remember for mimo to work every connected device on your wireless network must be running at wireless N. If there is a device that is running at g it lowers the mode to g for the entire network.