Tipping in Germany: I had a big discussion about this with my hostess (a native German) in the Black Forest some years ago. She told me in no uncertain terms that I should never do more than round the bill up to the nearest euro. Of course, she was Schwäbish, which are the German equivalent of the Scots. I can't bring myself to give a 10 cent tip on a bill of 9,90, so I customarily add 50 cent before I round it up. So 9,90 euro plus 0,50 is 10,40 which rounds up to 11,- euro. That's an 11% tip, not too bad. When I get to higher amounts, I customarily add a few more euro.
Tipping in Germany is not so much a gratuity for good service as it is kind of petty to take the small change. That is, unless you get into a very touristy area, where they expect Americans to be BIG tippers.
I should add that when I had this discussion, Europe had just gone on the euro, which was worth about 2 DM, so, in essence, they were having to round the bill up to the nearest even DM. I think some of the Germans were still seething over this.
Generally, you do not wait to be seated (unless there is signage to the contrary, which you can't read). This, in my opinion, is one of the neat thing about Germany. I've had many a nice encounter with people I met because they sat down with me at the same table.
In general, Germany is a cash society. I find that small hotels and pensions don't normally take, or want to take, credit cards. If you go to a place that accepts credit cards, you are probably paying more than you should. The same would be true with small restaurants. Major department stores and German Rail will take credit cards for purchases without blinking.