An adjunct of this "the good of the group" mind-set is that punctuality is quite important in Germany. Arriving even five or ten minutes late for a meeting is considered disrespectful. So if you are running late for an appointment, it is best to notify the person in charge. Keep in mind that it's not just the expertise and skills you brought along with you which will insure you success in your business here in Germany. A good way to maximize your chances for success is to learn some of the small but important German customs that cross over into office life.
For instance, when you have a birthday here, you're the one who throws the party - even in the office. You'll be expected to provide a small array of edibles such as rolls, cold cuts and maybe small cakes or cookies, perhaps pretzels. Quaffs for the party would include the obligatory bottle(s) of Sekt (the German champagne) and juice or mineral water for those abstaining.
How much you buy depends on how many are in your core group. (Go easy on the Sekt, as you want the staff to get some work done that day, but each person in your group should get at least one small plastic cup of the bubbly to toast you.) In return, you'll probably get a decent group present that everyone chipped in for. And don't think you can get away with skipping this practice by pretending it's not your birthday. People in German companies have this preternatural ability to discover upcoming birthdays of just about everyone in the office!