We had some unexpected issues pop up during the rehab that cost us money.

On a side note just to add some perspective - there's a decent chance you're going to run into 10k in unexpected costs within the first couple years of ownership, and that's part of the business. 

Then I would make sure the house is-1. water tight - fix the roof2. all working parts are still working ( water heater, furnance, ect) and no exposed outlets or wires3. broken windows4. tight doors5. no flaking paint exterior or interior6. flooring - safe to walk on7. fix or remove rickety outbuildings8. pleasing to the eye from the outside ( well trimmed shrub & trees)This is what I learned on my first buy and it just cost me 3 returns of the appraiser to get it right.

Old paint on the outlets!

With my first inspector I learned about bathroom vents, electric codes and GFCI outlets, termite damage, wood rot, how to check for leaks, etc.

If one unexpected thing goes wrong, and you are in big trouble.

Go with the applicant that you feel visualized themselves in the house during the inspection...did they look at outlet locations?

Wholesaling is not a recommendation unless you have a crew and serious connections, plus outlets.

This was unexpected because, even after the initial introductory period was over back when I first obtained the credit line, the bank continued to offer the 0% promotions again and again for years.

Plus, you'll want to create an upfront operating account of 1% to 5% of the purchase price to cover unexpected expenses before you've accumulated enough money for the $250 to $300 savings.For SFRs or smaller multifamily, as you said, it depends.