I'm particularly wondering if there are any technical skills I should hone to give me leverage in the job market when the time comes. Or opposite, any "bad habits" I may have picked up from US companies that simply don't exist in European engineering culture or decision making. Are the interview processes similar to the US?
The biggest issue will be cultural. Don't be a workaholic. Don't live to work. Don't bring that culture here. It is fine if you like to work, but don't project that as expectations on others.
Source: I'm US person who moved to Europe. I've worked for US companies as well as global and European companies.
It's a different culture. That you'll need to spend a lot of energy to understand.
Also german is a hard language to learn. Typically US people got it easy and don't understand such complexities, but this can be a time consuming endeavor.
Typically Americans have a very naive understanding of how the world works because American imperialism made it easy for them. So you'll need to get over this obstacle when you move here.
I believe it's worth it, it will open your eyes for many things and will make you a more complete human being.
BUT beware, all Americans I know moved back to US to make more money. Often they move here because they believe they are more left-leaning and like the idea about social democracy...
But then go back to the US because everything is easier there, salaries are higher (as long as you are a white-collar worker).
Feel free to mail me, I've been living here for 10 years and can help you understand what you are getting into :-)