One of the challenges I can already see is understanding permitting and zoning restrictions for STRs depending on the market. 

Are they pulling permits on the property ? 

Make sure the driveway/lot/street drainage does not go into your front door or garage, many do.Be aware that many houses started as Summer cabins in the 1950's and were added on and added on without permits or any building skill. 

Same goes for property management and if you start a contracting company to pull your own permits.

My partners and I have a piece of land almost ready for permitting for a multifamily. 

One of our clients did receive a violation from the city because the neighbor complained about an un-permitted garage conversion.

.- Review Historical Permits: Check with local building authorities to see if the previous owner obtained the necessary permits for the repairs.

Permits are very difficult to obtain (we build homes in Chicago, so that may be a non-issue for us considering what we have to deal with here LOL :)4.

As of right now, there are 3 existing permitted structures: main house, detached garage in front (600 sq ft), and huge 2-story detached storage unit in back (2400 sq ft).

We went into a project with a handyman, and after 95% of the work was done, had to pull a permit for siding with an outside company, which got the county looking at the windows, which our 'handyman' didn't do correctly.