4.5" coils vs 3.5" coils, just throw them on and make the appropriate adjustments in the track bars and control arms. If you are really compensating for sag then you really should not have to do much in adjustments. Just let it be known that just adding height will do nothing to prevent rubbing on the fenders when you stuff the tires. If rubbing is an issue now with 35's I would say you don't have your current kit properly installed.

 

Just going higher isn't going to help with 37's.

You can do 37's with stock fenders, but not without bump stops and trimming. I have 37x12.5x17 Toyo RT's and a RK 2.5" lift. You will also need wheels that have at least 4.5" of backspace or the tire will hit the outer edge of the fender.