They are getting what they really want, and you are crafting the deal to where it will still make sense for you.One potential issue is if what is most important to them is also important to you.

Whenever you are using leverage, you need to have ample slack in the system and sufficient cash reserves (or access to cheap & instant cash) to cover vacancies, capital expenses, unplanned maintenance, and other issues to avoid missing your note payments. 

She is requesting I reimburse her for the $150 she spent on these very specific particular wall anchors, if she needs to replace them.

I'm not proposing to change the landscape and what the properties I do have noise and parties have not been an issue. 

What specifically will they be doing?

What other issues/roadblocks may I face that I am not aware of?

It depends on various factors, including your experience, market knowledge, financial situation, and the specifics of the property and location.

I try to spend a little more time initially on making sure the maintenance is up to par when I buy a property and I rarely have any maintenance issues.

Bian- I co-own a HOA management company that specifically works with smaller buildings. 

Rental Demand - higher the demand on your rentals, the more likely you won't have any issue having tenants pay for water.