Even Those that I reached out to when arranging for large problems like flooding or no ac in summer go back to the PM once the problem is solved.

May I ask how you arrange to have traveling doctors and nurses stay at your Airbnb?  

There are no written contracts for any arrangements made between the two parties. 

I thought that the preschool and child care tuition should cover the cost for the their use of the building.

I have possible arrangement with my brother.

If you are keeping the same residents and want them on a new lease, make sure you give proper notice of rent increase, (in my market its 30 days for a mtm tenant and 60 if they are on a lease) and a good strategy that I got from these forums is to increase it the most for a Month to month arrangement, and to increase it less for renewed lease.  

I've never heard about this strategy before and curious if anyone has done it, pros/cons, and what the execution of such an arrangement is like.

We were able to get the house $20k below market value by securing a realtor that took a reduced commission since we had arranged all aspects of the deal.

Are there any verbal agreements or arrangements between the current Landlord and Tenant?

HOA should have made arrangements with you weeks in advance.