It is a separate legal entity.

Consider Hiring a Legal Expert- German property law can be complex.

I am assuming short-term rentals would be legal in the municipality.

Will the title company put this property under our LLC name, and won’t be required to legally inform HUD/tax authorities. - will it influence property taxes once we move to conventional loan in 3 yrs? 

With the internet, there aren't really do overs -- most websites have other websites that grab (legally or illegally) information . . . it is pretty impossible to make anything disappear once you put it online.

Long term $ can range from 6's-10% range depending on all types of factors - LTV, location, unit count, debt coverage, borrower strength, full doc or lite doc programs, etc..

The real prohibitive costs come from the legal, compliance, and reporting requirements of registering a security.

However, you can get loans that are based on the performance of the rental and not your personal income and debt.

Once repositioned the expected CF could be approximately $30K/month, less the debt owed for getting into the deal.

If it does go to probate, hopefully your brothers and you can amicably go the informal route vs formal (I've worked with families in both when buying properties out of probate and informal is FAR easier).Since there's no debt on the house, maybe you could sell with financing or maybe you could even buy out your brothers with financing -- that way you maintain ownership and just pay them a monthly amount.