When PCSing to Germany as a mechanic, will I live in the barracks or will I be able to get a house? Also, how is being stationed in Germany?

Depends on the base/kasern you get assigned to. Plan for barracks life, though. As for Germans speaking English, yes for the most part they do. However, it will go a long way if you try speaking Duetsche first. Also, if they still do it, you may very well go thru what is called (when I went thru it) Headstart Program. There, you'll learn some passable German language skills and learn about some of the culture.

take the time to learn at least conversational German. Goes a long way, no matter what country you are in

If you are single you will live in the barracks. You should try to learn the language of any host country. It is a sign of respect and they appreciate the effort. Germans do speak English at varying levels. I did learn German. Germany is a wonderful country full of great people. You will enjoy it if you try.