Stopping rust in hard to get to places?

[mike14_07]

i just cut out my inner rocker and cab corner and i want to put something on the insides of the cab supports to prevent rust. what is best and also what is best to paint my floor pans with in the cab and under. also if you dont mind telling me what steps you did from bare metal to done. and what kind of seam sealer works the best for unseen seams and whats the best for the roof around the drip rails.