Keep in mind, its only really relevant for me if I'm trying to qualify for more vacation/second homes. 

so I can try to give you relevant information. 

It's probably much more relevant in a buyer's market.

“The Wright Real Estate Team” – I’m not sure how you concluded that the company is owned by his mother, which it’s not, but I fail to see why this is relevant.

Your depreciable basis is what you paid for it 31,500 (less any value allocated to the land), the other information you have provided has no relevance.

not sure what else would be relevant and don't want to bore you with details.  

I tried looking at several software tools, but most of them include features that are not relevant to my use case and are expensive as well.

So if the owner has agreed to forgive the last month’s rent, then why is the security deposit relevant to the seller/landlord? 

So, if any of you have some experience in the real estate market in Germany, or merely some ideas, recommendations (relevant books) or leads regarding from where should  I start my journey, I will be grateful to learn from you. 

My 2¢...Like many said before, if you pay yourself through a separate LLC, you would have to pay income tax, state and local taxes (if any), and social security taxes (which might be of interest if you want to accumulate the annual points towards SS...and of course, believe SS will be there to pay you at retirement any relevant amounts).You can setup things such way to pay the least amount of taxes, for specific gain and interests.