He was used to a 1 1/2 page contract that covered "everything" (but really didn't).

We're talking new roofs, new interior layouts, bathrooms, kitchens, everything. 

The original plan was for the tenant's side to pay 100% of the mortgage / taxes / insurance / PMI, while I cover trash and water for both sides. 

You'd certainly want to have an umbrella policy in place, in case your business insurance policy doesn't cover everything.- You mentioned mobile bathrooms (hopefully not port-a-johns). 

Rent covers a lot of different expenses that new LL's don't see going in, then try to recoup from tenants. 

The roof, appliances, driveway, etc. will need to be replaced in time, and the CapEx is used to estimate those long-term replacement costs.  

Is the home owners insurance covering the cost?  

What if it needs a new roof but inside if mostly ok?

I assume it's just the bigger stuff and single family homes (electrical, roofing, etc) but just want to make sure as I want everything done the right way (not always common here in Miami.)

After buying the property and viewing it I quickly realized why noone had rented either of the vacant units: both units had what looked to be mouse crap on the floor and the other unit had a broken window (not cracked - a literal hole in the glass) and there was a hole punched in the drywall (covered using cardboard).