Default [Q] Android gamepad

Hallo, I'd like to buy some bluetooth gamepad from and I have few questions. Is anybody here, who has ever tried to connect wireless controller to android? I like this one

Do you think it will work to me if I haven't ROOT acces. Will the controller connect as well as for example bluetooth keyboard or will I need some app?
And my last question. I Know many apps does support gamepads, but if doesn't, is here any way how to map buttons with using another app which doesn't require ROOT acces?
Thenks for the reply.

PS: Excuse my English it's not my mother language.