I have read about some cities limiting the maximum unrelated renters. 

  - I'm sure you've thought of this already, but your town doesn't have to be tourist-heavy to be a good airbnb location - I've seen wildly successful short term rentals located near universities and hospitals and nowhere near a tourist destination. 

No war zones in any of those cities.

@Kai Van LeuvenIt’s sounds like you’ve gotten all the low hanging fruit, another couple things that come to mind Is reducing boring expenses that people typically dont shop or spend alot of time addressing;-taxes ( I don’t know how tuned in the city is to your remodel but you want to spend a little effort ensuring you don’t get hit with a property tax increase )- I’m not sure the type of tenants your looking to attract but a playground might go a long ways to adding value-Insurance ( anything you cad do to reduce your insurance?

I would file the federal tax return mainly for the ECI declaration and to submit the city return which is mandatory anyway.

What counties or cities are you focusing on?

You cannot buy it from the city or county before the auction as they don't own it. 

I'm relatively new to real estate and have flipped one out-of-state property in Kansas City, MO.

I can't speak to many other cities but Calgary is in a state of cooling after oil took a tumble. 

Nashville has been blowing up and I know that's forced appreciation into some of the suburbs and surrounding cities.