RealGM

I kinda understand the general idea, but not really. Could someone link me some articles or threads (or just explain here) the pros/cons of them? Stuff like RAPM, APM, xRAPM, etc. As many and as thoroughly as you are able.

Here's a good starter

http://godismyjudgeok.com/DStats/2011/nba-stats/a-review-of-adjusted-plusminus-and-stabilization/

It's also explained in this book
https://www.amazon.com/Handbook-Statistical-Methods-Analyses-Handbooks/dp/1498737366/ref=sr_1_1?ie=UTF8&qid=1492590168&sr=8-1 but that's obviously not for free (but has some other good information)