Although the cosmetic finishes look quite good, there are some fundamentals which could pose future problems -1) No arc flash breakers (AFCI) at the electrical panel - house was built in 1996 prior to the new legislation kicking in, but this is not up to code. 

In most counties, " Any federal Internal Revenue Service liens that, pursuant to provisions of federal law are not discharged by the sale, even though the tax collector has provided proper notice to the Internal Revenue Service before that date.

Was there any federal legislation passed?  

Remember that our thoughts generally control our actions which intern create a result, the problem is most of the time we don’t accept the results and/or the consequences after the fact.

Our goal is to airbnb this house full time since it's in a great market 5min away from the international airport in phoenix, but curious if I should operate it under a "lease contract" to be able to qualify the income toward the next place.

Real estate is something I’ve always wanted to invest in but the prices in the UK along with the type of bank loans, and govt legislation have been making it more and more difficult. 

While I have zero experience in STR "innerhalb von Deustschland" I am curious as to why these specific areas- and while I don't know SFR legislation per region, with STR in mind I might only suggest to look into Berlin as a more lucrative area- thinking along the lines of tourists specifically.   

Another path, you can try to help as an  intern for investor and learn to do BRRR and flips and chart your own path that way too..

My BIL and his wife are quite well off, he a retired doctor, she a high level executive, a Senior VP with an international bank recently assigned to Singapore.

I am by no means an expert in international Tax, but selling homes in Texas couldn't be easier.