Educate yourself with resources like The House Hacking Strategy and practice analyzing deals using tools like BiggerPockets calculators.

Private money lenders are not always individuals (my company, for example), nor do they confine their lending practices to friends, family, and other investors they know.

The area has certain advantages like shelter from regulation risk (pretty much as low as anywhere in the country if you buy in the approved STR tourist zones) and long term security (people aren't going to stop going to Orlando anytime soon). 

For large apartment projects, it is not practical to demand the return of all letters before closing.

No, it is inside of an HOA neighborhood but the current regulations only restrict rentals under 30 days stays.

Airbnb properties can be hit or miss depending on location, seasonality, and regulations.

Practice Pitching: Sellers may not be familiar with subject-to deals.

Started with the flip business 2 years ago and going strong. id say start by practicing comps in your area, learn your market and go to real estate meetups.

No, it's not a normal business practice and does not pass the smell test.From driving? 

Another common practice for nationally sparse datasets such as tax data is aggregation.