You'll ahve better luck looking for answers to specific questions. I know of no manuals available online. If you don't mind using p2p software, you can try to get it through kazAa or whatever people are using nowadays. Back in the day that is how I got a lot of software, media, etc.
I recommend you get the Bentley manual for the 3-series. It will only run you about $50 shipped free from amazon: well worth it.