re: Germany for work and vacation

If you don't see anything during your work days, you should plan to spend a few days in Berlin. Lots of sights if you are into history. Afterwards you could go east to Poland, south to Prague, west to Hamburg, or southeast to Munich. All are just 3-4 hours by train.

For business... are they customers, partners suppliers...?
There aren't any crazy customs. They are more formal, put more importance on title (are you a Dr?), and put a lot more importance on the specific wording in presentations and are more precise about meeting minutes. But they are familiar with international customs and aren't really offended by much. For food and dining, not much too worry about. They hold their fork in their left hands and make fun of Americans that cut everything up first and then eat the pieces. But being the pharmaceutical industry, they won't be too parochial.

Have fun and enjoy the beer!