Sounds like its time to hire a bookkeeper!

I think there are other areas that are more exciting for a long term appreciation hold, but if your just looking to bank some short term cash flow and then add value to sell I think this sounds like a good opportunity for you! 

On one hand I think I dodged a bullet with this person not moving in, bc it sounds like it would be a year of complete chaos.

@Dominic Nguyen It can be done but just from what it sounds like you have a lot of good questions!

However, based on what you stated your goals are I think buying the next house sounds like a better option to reach those goals.  

This ADU will replace a small garage storage that I rented to my front tenants.

If this was a standard rental process then yes, I'd recommend going through the process of applications/screening steps, a background check, and then require the deposit; since it sounds like the house is being rented to transient workers though, the very nature of the work situation calls for a bit more flexibility on the renting end. 

Could anyone refer me to a contractor who could replace the ceiling?

Personal Property: $30,000                    Personal Liability: $300,000                    Replacement Cost: Included                    Medical Payments: $1000                    Loss of Use: $6,000                    Property Damage to Others: $500                    Mold Property Damage: $10000                   Mold Liability: $50000                  Tenant Pet Damage: $500                  Additional Interest: Myself (the landlord)2) With above coverage added to renter insurance, do I make it mandatory for the tenant to have a separate pet liability insurance?

If you supply the appliances, then you have to repair and replace them.