I have a beginner coil rider question.. I recently picked up a rocky mountain flatline pro that came with a vivid 4.1 and my buddy just picked up a trek scratch 9 with a vivid rc2. Are the springs interchangable? He has a 400 lb spring an I have a 450lb spring, and we want to swap them.. can it be done?

Also, when turnin the rebound screw on the rc2 can you physically unscrew it ? Cuz my buddy was messing with it changing the rebound setting an probably 12 clicks out, an it started leaking oil...