Maybe a small beauty parlor, nail salon, art studio, music lessons, or specialty sales books, clothing but it is anout what the area would support, what's missing.

Electric nail guns.

@Barry Je, @Michael Le pretty much nailed it.I would say you could also get the help needed by partnering with an experienced sponsor.

If you've got these things nailed (which in some cases, is easier said than done), the rest should fall in line without too much trouble.

I recently served one of the tenants with a 30 Notice to Terminate Tenancy (tenancy less than one year) though the nail and mail method.

Meaning, your attorney really needs to nail all this down in a watertight agreement in order to avoid that the owner suddenly sees the gold himself.

Plaks nails it.

As for your questions -  @Tim Swierczek and @Jordan Moorhead pretty much nailed it, 1) When doing research, I use zillow, hotpads, apartments.com, craigslist, and rentometer.2)  I'd say in general SFH are actually more attractive to tenants because they get more privacy. 

I want to nail down a true number and not something inflated.

I think that @Cara Lonsdale hit the nail pretty close to the head on this one.From my experience, for a residential (1-4 unit) loan, the bank is going to use standard underwriting practices including DTI (unless they are going to portfolio the loan, in which case looking at DSCR would be the wisest choice in my opinion).However, just to clarify a bit:My experience is that they are going to do a personal DTI, not a property-only DTI (again, unless they portfolio, in which case they can do whatever they want).