I can't find any good learning resource on AOSP. Can't find any books, or comperhensive web resources on that topic. Book that would cover all topics about it would be best. Like how to setup enviroment, download code, use repo/git, change basic things, make custom roms, etc etc. Is there any book like that? Or any other resource on web that have that info in one place?
Karim Yaghmour's embedded android covers a fair bit of AOSP stuff. There are some good videos by Tim Bird and Yaghmour, google for those.
If you want to create custom roms you probably want the xda-developers and their forums or cyanogen.
Repo docs are fairly sparse: see this post for that.