I've never had complaints but my Padsplit is very well suited. 

If you stay on the mortgage, you need to write out a legal agreement as to what happens when she sells (or if she finds another boyfriend/gets married). 

Is there a legal way to ensure they dont trash the place?

There is a possibility that you could keep this buyer under contract (for example if he tries to cause you legal trouble) if he is willing to wait (which he will if he is an investor who was underpaying you what you think itis worth As Is. 

I carry a very small, very light 8 shot 22 caliber revolver everywhere that's legal.

They say this can take 30 days, yet I see complaints on BBB and the App Store for Google and Apple where people have not gotten their money back yet even after several months.I have contacted my bank and they said you have 60 days to file a dispute from the date of your DEPOSIT not the time you request the transfer back into your bank. 

That is basically an extra tax return, legal fees for setup, bookkeeping costs (if you aren't doing it yourself), possibly an umbrella policy.

If the rents were collected after closing and they were not addressed in the sale, then you shouldn't have a legal obligation to give them anything.

If you use a DSCR rental loan it could be as low as 3-6 months of time seasoning required so it depends on what product you're using to accomplish the mission/goal.The time frame isnt a legal requirement, its a financing product specific requirement as a guideline to obtaining the money in which you seek.If you had other scenario related questions feel free to mention them below or via DM.

BP has some and also you can use Legal Templates to create one.