Android processes? How to See What Apps Are Currently Running on Android leads you through it (with screenshots). Don't be surprised, though, if you disable a background service and it starts up again. Android knows what has to be running better than you (or I) do. (Light Manager has to be running? That surprised me.)
OS services? There usually aren't many - the main one is, of course, Android. (The OS is Linux, and if you run ps in a terminal app, you'll get the list.)