@Colin Caporal-  extension fees  of 1.25 to take the  6% rate to 8.15  is  standard and OK  ...but ..you should ask the  question  about  what  happens if the  house and loan arent  closed  by 8/15/2022....(   this  could easily  occur  and  you want to  have this  issue  addressed  now  versus later )  ...were you able to  get the  DTI issue  addressed

@Gabriel Ramos yeah, this seems to be a pretty standard renovation loan.  

The standard is that your intent must be to hold those properties for productive use in business, trade, or investment. 

First and foremost, whatever you are doing, you must keep the Federal AND State Fair Housing laws in mind: Treat everyone the same, using the same standards.

@Pete Largo, while I would say 10% is an industry standard, I see many, many deals that are far less than that.  

Apart from the standard legal terms of a lease agreement, is there anything that I should consider adding to the lease that would not typically be already written in the contract?

There are noise standards no matter your mental issues or the issues of your child.It is wrong to decide one tenant can be destructful to another because of a medical condition.

I don't have anything to offer with your question beyond what everyone else has said but I just want to let you know some general rules with foundations:1. crawlspace - cheapest to repair, good for plumbing because they can run underneath the house and easy to repair, bad for really cold days, pipes could freeze, some people complain about moisture in crawlspace and tile cracking but that's a long term issue and you may not have to deal with that and if you do, just lay LVP2. slab - second cheapest to repair generally, worst for plumbing because to fix, you have to often remove flooring and drill into the concrete to fix leaks and I've had a house that I played whack a mole with an active leak3. basement - most expensive to repair, okay for plumbing, but your basement could leakIMO crawlspace is the gold standard for foundation for rental investments in older properties (older than 1950s).

We like the gold standard of FDIC insurance for each account. 

I hope I don't come off as brash, but my first instinct is that the rent is either too high or the condition of the unit is of lesser standards to your competition.