I am an American living in Germany at the moment and plan on moving back stateside next year. However, I would like to start an online company before that time. I have two major questions I have to tackle right now. But first I will explain that the company will be strictly online, not brick and mortar...and I will not be selling any physical products..only acting as a middle man, offering customers a website where they can pay to list their properties, and others can come to the site and search through the listings. So the profit I make will strictly be on selling memberships to customers. Now the questions:

I am legally only allowed to make money in Germany as an English teacher. However, an online company isn't specifically making money in Germany is it? It's an international market. So this should be allowed, right?

Which brings me to my next question...how do you even register an online company if their is no physical office? Is it based on where you live? So, if I start the company now, I have to register with the German government? I want to avoid this obviously because I am not allowed to make money outside of english teaching. Also, because I am moving back to the states next year, I plan to open an American bank account for this business. So the profits collected will go to an account in the US...which is what should determine where I register the business, right? Can I just do the whole thing in the states even though I'm not there yet? I am completely lost on what needs to be done in terms of registering my business, what taxes I have to pay, etc. From what I read on SBA.gov, I don't have to pay a sales tax because I'm not selling physical products. Is this correct? It looks like I'm going to have to pay a lawyer to sit down and talk to me about all of this but in the mean time any help from here would be appreciated immensely!! Thanks