It is pretty easy to keep it fully occupied but it does mean I turn away a ton of people who want a lease that doesn't quite fit my requirements. 

You should not get a PM until you have scaled to a level that requires it.

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

These are all important considerations, and understanding the requirements can save a lot of headaches down the road.

High credit scores and low DTI are often required…and these take much longer than I first thought…Navy might take 45 days to get through the gauntlet.  

@Kyle Trotman If you purchased with a hard money loan conventional lenders will require extensive seasoning to utilize the new appraised value for cash out. 

I don't ever stiff the housekeeper and if this was a long term tenant who needed to break early I would do it but probably not in this case, again unless regs require or mom presents a more compelling case. 

The lender will require that you live in it for 12 months and then you can rent out all of the units after that and start the buying process using the same strategy all over again after that 12 month period.  

REI is full of surprises and they all require money.

If the latter, simply give her the notice required (eg 30 or 60 days) that she needs to move.