$500,000 after taxes is likely close to $325,000(maybe more or maybe less).Assuming cash-flow from rentals is offset by depreciation, you would need $325,000 of annual cash-flow from the rentals.If you can get $200 / door / monthYou would need 135 doorsYou can work on this type of math to figure out how much rentals you need.Be mindful that rentals require some type of work.

Best way is door knock, cold call and do the dirty work to find those sellers needing to sell.

It's a great way to get your foot in the door in your local market and offset your mortgage while building equity. 

.- Most cities do NOT care if an owner lives in basement, but will not allow a tenant to unless baement has legal egress window.3) Check local statutes if any limitations on how many unrelated roommates are allowed.4) Check with local building dept to see if rental inspections and corresponding requirements.5) Local statutes allow locks on bedroom doors?

What do other property managers consider, actually do, or add to their tenant screening criteria to cover retirees?

Did you check a next door comp that just went into contract?

. - Then the next filter is physical property attributes with regard to its placement in the market, entrances, and exits, visibility etc

From there, it's a comfortable drive on the highway, which will take you a conservative maximum of 2 hours door to door.

There are 3 bedrooms upstairs, and 1 bedroom/bathroom in the basement, there is also a separate basement entrance. 

Are there separate entrances and exits?