I would not coat the frame with anything but paint as any type of coating will eventually lose the bond between itself and the metal but stay intact forming a small void for water to be trapped, corroding/freezing etc. At least with high grade paint when it fails it will flake off and you get some kind of warning the coating has failed.

I think with the lift, upgraded torision bars, and stiff sidewall tires you won't be able to tell the difference with the sway bar on or off. The lift won't stiffen your suspension but it will feel that way due to the change in angle of the a-arm.