Can I get my bachelors in a university in Germany then head to USA for medical school?

Sure, but German schools are also quite exclusive - not everyone gets in. And you'd have to learn German.

European universities don't work like American universities. Chances are good you would not be able to take the pre-requisites, which span bio, chem, physics, math, English, psychology, and sociology.

You must graduate from a US university to get into almost all Medical schools. Actually, I doubt if there are exceptions

Some US med schools do not accept foreign-educated students. Those that do usually require you to take all the med school pre-req courses in the US. Some require a year's worth. Some are fine with your entire education being done overseas. For example, Johns Hopkins does accept foreign educated applicants, but they require that you have spent at least a year at a US uni:
http://www.hopkinsmedicine.org/som/admissions/md/application_process/international_applicants.html

Due to how European degrees are structured, you would not be allowed, normally, to take classes outside your field of study. So if you were studying, say... biology, you would not be able to take the psych and English pre-reqs required for most med schools.

So long as you don't mind these things, your plan is fine. Just know that it may limit which US med schools you can apply to, and that you may have additional coursework to do in the US before you can apply.

Keep in mind that normally, medicine is a bachelors degree program in Europe. It may or may not be possible for you to study medicine for your bachelors in Germany. If you can do this, know that it may be possible for you to practice in the US. You'd need to find out if your uni is allowed to have you sit the USMLE, and you would have difficulty getting a US residency, but this may be possible.

If you study in Germany, tuition there is free. However, you still need to pay your room, board, and travel. And most US sources of financial aid for college won't apply to your studies in Germany. So it may be a good idea to apply both to German and to US unis. See where you get in, see what aid the US unis offer you, then decide.

There are a few programs in the US that make medical school either free, or will pay back your loans. Including the military. So as you get closer to med school, begin to research those programs.

Possible, yes. Probable, no. American medical schools prefer that you get you science and lab prerequisites at an American university.

You complain about the cost of education here, but to study in Germany you'd have to put up enough money to cover your four years of university and living in Germany and keep it in the bank as proof that you wouldn't be a burden to the German government. That's probably not going to happen if money is an issue for you.

You would have to apply to med school and there is no guarantee they would accept you and the bachelors, just like any applicant.