I basically want to perform my bumper conversion before I primer the body up while the motor is out, that way I can hit the engine bay also. My question is, how hard would it be to swap the S5 bumpers onto the S4 Chassis? I'm trying to be as clean and neat as possible and those bumpers(front & back) would keep my goal in reaching limits.

Also, Is there a certain type of way I should go about doing the engine bay? Should I use a different paint and primer from the outside that well stand up to the heat in the engine bay?

Lastly, i'm still learning everything as I go. So I want my car painted blue. Like a litter shade(like a smurf). But as far as primer goes, which color would be the best base coat for having the blue laid on it? My guess was a greyish type, but i'd rather hear from others who have knowledge already.

Thanks,
Antaous