The costs in TurboTenant are the background checks a new tenant would have during the screening process, which the prospective tenant pays for as well as a small charge to have Digital signatures on documents that I store online (it's $9 and also charged to the tenant).Beyond that, I use google docs (mostly sheets) for my underwriting/review process.The only item I pay for is Quicken, which has a yearly fee now.  

This being said you can still screen the tenant like you normally do a market rent tenant, and you should.

How much can I get involved in screening/selection of the tenant?

Go to NETWORK at the top of the screen.

If you want to scale quickly, I recommend medium sized multi families in affordable markets with reasonably low property taxes.

@Di Ye Whatever you do and whatever your method of screening... you must remain consistent!

You could qualify for a good size loan and/or multiple mortgages for multiple properties, this assumes you don't have car and student loans and other bad debts. 

I am poised to make another decent-sized investment so keen to see what this does to the market, specifically in North Carolina.TIA

I'm not a lending professional by any means but depending on the size of the multifamily, you can get a conventional loan for as little as 3% down.

Is that size accurate, I think you may mean 0.23 acres each.