Our last 15+ tenants that we've placed we've required online payments.

Costs vary but can range from $1,000 – $3,000 per unit.Water/Sewer: This is more complex and may require approval from your local water authority.

Its great that the seller is will to carry a note in a seller 2nd as well, that will help reduce your require monthly payment with the right lenders.

Check AirDNA for demand, pricing, etc.The Dekalb Board of Commissioners has proposed regulations for short-term rentals. https://engagedekalb.dekalbcountyga.gov/airbnb-dekalb-countyShort term rentals require you or your property manager to be hands-on and come with more risk.

Just my personal opinion - get a mentor or a person who already has good experience running STR business, preferably in your area (but not 100% required). 

You simply get a discount on this purchase, equal to your tax rate/bracket.

@Helena Goyvaerts rate for a 30-year fix would be at least 8.5% with some points (1% of loan amount).Most DSR lenders have a minimum credit score requirement from the applicant.

Maybe you could extend the closings with some additional earnest money (even if you release it) and buy the time so you can simply do a regular 1031 exchange.  

The PM business is not an easy business and most have fair fees for the work that's required.  

These need 20%-25% down, require a 680-700+ credit score, and 6 to 9 months of reserves (reserves are payments in the bank).