@VC the other threads vary as each person's experience seems to differ depending on lots of different factors, including alphabetical order. It can really suck if your last name begins with a popular alphabet letter. Anyway, for what its worth heres my situation: I was recruited from the US by a German firm for a short term post. The firm did all the leg work for me both on the work permit and the residence permit. All I had to do was show up.
I was advised to bring with me to the residence office: copies of my work contract, cv, work permit (the residence permit was dependent on gainful employment), passport, and local contact information (work and private) and 2 passport photos. I double checked everything with the consulate, their checklist was different. For example, although the work contract specified my salary and insurance benefits, the consulate advised me to bring proof of US income (last bank statement) and health insurance. However, the most significant recommendations were a recent clean bill of health statement AND proof of good LEGAL citizenship. If you want to do this, you can go down to your local precint, get a background check and get them to write a statement saying you are citizen in good standing etc. etc. I thought this was absolute BS but I did it anyway. BTW: the police new EXACTLY what I needed, apparently this is standard for visa and/or immigration purposes into many countries. (This makes no sense as you could've committed mass crimes in another state but whatever, they didn't recommend a Federal check;-)
I got a great guy, only major complaint was that he and his office mate were both chain smoking with the windows closed (winter time). They had one puny little oscillating fan to help "circulate" the air but that just made it worse. Anyhoo, I'm positive that starting off on the offensive, i.e. plunking down my big fat organized binder AND being accompanied by a bonafide Bavarian ensured that I got very politely rubber stamped, no questions asked. He was very cordial, efficient and sincerely (no kidding) welcomed me to Germany.
If you want to pick between any of those, I'd say bring the passport and the Bavarian