It seems like each option could work depending on your long-term goals for those assets.

Rent probably around 1400-1500/month depending on finishes and exact location.The number simply don't work well in Huntsville right now.

I like the idea of no pets and that is decent income (depending on what the rents are).

Depending on the application, first, last, security, and another month or two.

They have a form you can fill out and submit, might be able to do it online depending on the city.  

Maybe it can help you in your specific situation, it depends.

Depending on your area, it can be a pain to set up multiple LLCs and keep them running.

A general rule of thumb though (not a hard rule) is that if a market has a prolonged history of vacation rentals such as towns whose commerce is very dependent on tourism like beach or mountain towns, then there is a good chance than those towns have established their airBNB regulations decades ago and are likely stable.

Note this can be pro or a con depending on your strategy.

Charleston etc. is that folks there are HIGHLY dependent on local attorneys to do their paper work/ escrow functions prep deeds etc etc.