[Mr.ac]

You could do get by with a 2ch amp and speakers. If it was me I'll go for a 4 channel just incase for the long run. That way you can add a low power sub and keep the fronts amped up. Or not. But you'll have the option any time you want and not have to buy another amp.

I would add some sound damping to the doors. That would make it sound a notch better.