The experience i gain will ideally coincide and strengthen my future buy-and-hold rental portfolio.

Not sure what is legal in your jurisdiction, but you could consider using all kinds of things as collateral: life insurance policies, future paychecks, artwork, etc. 

Will it cause problems with future renters or resale? 

A living trust can be a great tool to not only let you dictate the future of your hard earned real estate portfolio while you are still alive but can help reduce estate taxes, ensure a step-up in basis of your properties to eliminate or reduce capital gains and avoid reassessment of your properties when you die so there won’t be a large increase in property taxes.Long story short, please go see an estate planning attorney!

While I can pull in money hand over fist, my concern is that a 90 year old building in such a small area might be hard to get rid of in the future.  

Some of the others are a little to expensive for me right now but I wrote down the information on how to get access to it for futures sake.Thanks Seth!

Ethereum, which has a practical business application in that it provides a platform to build decentralized applications, which is THE GOLD MINE BEHIND BLOCK CHAIN, as opposed to Bitcoin which is simply a currency).All that said, that's just my opinion (strongly based on my work experience and research) and the future could prove me dead wrong.

Upto this point their are no zoning laws making what we are doing wrong this may change in the future who knows. 

Unfortunately, the other is what it is and is set up that way  protect you as well as your future clients.

However; there's no guarantee of what the market in the future will do, as every area is different and it depends on supply and demand at the time.