If you can definitively prove that the seller intended to deceive you about the square footage for their personal gain, you may be able to take legal action, but probably low chance of success considering you had ample opportunity to measure the home or get an appraisal with measurements prior to closing, and had your chance to negotiate the price based on square footage and all other factors prior to closing. 

If you are a Landlord / Owner - you should WANT a commission based renewal fee. 

Even if you use alternative financing options that don’t require you to have an income most still require 10-20% down payment.

Your other alternative is hiring a listing agent to rent the apartment and they normally charge 1 months rent as well.

Study different exit strategies, choose one based of off your goals, timeline, and risk tolerance, then find a mentor. 

I'm not talking about a location based on tourism where zoning allows for STRs, hotels and they have existed there for decades.I'm talking about residential zoned areas.

You'll want to base things on the standard booking lead time for your market. 

My initial thoughts would be to secure a construction loan for the total rehab amount based on the entire property’s ARV.

I am a wholesaler based out of Washington State.

I used to get 25- 30% net caps based on cash purchases.