Unless the trigger spring is a problem, leave it alone in my opinion.
Stripping the slide for access to those springs inside is easy. Getting the slide cover back on...not so easy. I use a hammer handle on my 1944 P.38's slide cover, and a hearty 'whack'
The recoil springs- get a tool that has a hook on the end, drag back the spring and piston. You'll see where the piston slides out. Careful. You could launch that thing into your face
Mag spring is like any other magazine
Try:
http://www.p38forum.com/
If nobody's done a thorough write up, I'm sure they will have the advice you need for anything to do with your P.38. That site is worth a bookmark