The IRS sets the minimum interest rate, known as AFR - applicable Federal Rate.

There were a few question marks in the application but i decided to approve since both of the applicants were teachers and the one of them had a teenage child.

The lender will want to see that the income generated by the property can cover the monthly principal, interest, taxes, insurance and HOA (if applicable).

Screen applications?

Next applicant...

I am looking to get something like a Termidor application done.

Cash flow may not be positive after accounting for other expenses like your annual property taxes, insurance, and mortgage payments if applicable.

I recommend your purchase agreement include an opportunity to review any lease agreement, payment history, and application screening for current occupants.

I specifically need really user friendly accounting features (including ability to sync with quickbooks and print checks directly from the site/software), customizable online application, and online rent-pay as an option (hopefully with free or very cheap ACH). 

Most are actually pretty helpful if you reach out and ask questions in advance vs being hostile when they make you jump through hoops completing applications and preparing for the P&Z hearing.