Yes, you can do it, and it's a good thing for you to learn. With that said,
, yes, please do be careful and please do get the proper torque specs for everything that you're working on. While you're at it, go ahead and replace the brake disc, brake pads, ball joint, wheel hub assembly, all that stuff with new parts. Check out that axle, too; if it's good, you're fine, but if you have any doubt, then replace it, even though it's not cheap.
Regarding the control arm, if you see cracked rubber bushings, it's not a bad idea to replace those. If they're tight, though, this can wait a few years, but since it's apart anyway, now's a good time.
Regarding axles, I can tell forum members here that my S600 TT has 174,500 miles on it, and the axles (rears--all my Benzes are 2WD) are fine. Same with the 2003 S430 with 155K on its clock. So, it's entirely possible, and I'd even say probable, that the axle in that left front corner that Barmaley got second-hand is going to be OK.