Re: Traveling to Munich for a few days; What do I need to know/do?
The power voltage in Germany is 220V or 240V and 50Hz.
Make sure the adapter or other devices you connect to this power say it can handle 240V (this is even more important because it's
higher than in the US).
Most adapters on shaving devices, laptops, electric toothbrushes etc. sold in Europe are 110-240, but I'm not sure about the ones sold in the US. The connectors have two round pins and may have a ground-connection on the edge (probably not used by anything you take with you).
The adaptor you may need will look something like this:

They have different pins in the UK, but if you won't be there, you're alright with one like the above.
I would hesitate to buy a general 240V -> 110V power adapter: they're heavy and you may not want to take it back to the US. They cost roughly 30 Euros, but it may be wiser to inspect your gear before you leave to Europe and (especially if you think you may travel more often overseas) to buy a replacement shaver (or whatever) that can handle both voltages.
Cell phones are indeed GSM type, you probably need one with a SIM card. The frequency used is 900MHz. We used to have double-frequency phones (900/1800) for international use, but the standard frequency in the US is 1900MHz, so what we're using here now (if a world traveller) is a tri-band cell phone (900/1800/1900).
Unless you go to the UK, make sure you have Euros with you to pay small immediate costs (like a taxi to your hotel).
The language in Germany is German. (Surprise, isn't it?)
Most younger people will understand English, but this may not be true with older persons. Also, if you address someone, they may not realize immediately that you're speaking a different language so a first line may be met with confusion, even if the person appears to be rather fluently English speaking. People will NOT understand English better if you raise your voice or go on repeating something that's clearly not understood loud and insultingly slowly over and over again.

When in Munich, try some
Bratwurst.

(Don't go into Basil Fawlty mode, but no need to be really nervous about the topics you may want to discuss.)
Cees