Give Crutchfield a houtout for giving you measurements:
Front Door:
Size: 5 1/4", 6 1/2" (I guess either size will work?)
Depth: 2"
Height: 13/16"
As far as the head unit goes Crutchfield also makes good master sheets and mounting brackets and such. Shoot them an e-mail tell them your receiver and your car and ask them what you're gonna need, they'll be happy to sell it to you, hehe, and include extremely detailed instructions on removing your head unit and toll free phone support.