You simultaneously have an Option to purchase your house back for 1.1 million and you have a lease that you will pay to your new landlord which will cover all their expenses.

I would exceed the minimum requirements on this.Get a standard STR policy and make sure the pool is specifically mentioned and covered in the policy.Then you can look into an umbrella policy.

I'm interested in the outcome.From my understanding, only Licensed Contractors can slap a Mechanic's Lien on your property.If they are licensed and fail to show that they performed work for you without your permission, and are still able to slap a Mechanic's Lien on your property, this would certainly be unjust.It seems like an easy win if you take them to court since they could have possibly have a signed invoice from you.Did the PMC have power to sign Contracts for Work related to your property without permission?

@Ray Williams E&O doesn't cover slip & fall liability issues at YOUR rental.Doubt their commercial policy covers anything but slip & falls at THEIR office.So, they should want you to add them as additionally insured, so your insurance covers them for a slip & fall at YOUR rental.

Also, is this an additional cost you cover? 

@Stuart UdisLack Of knowledge and understandingMost take the guru course which only covers about 10-20% of what you need to know.

Are you planning on separating all the utilities for these units, so you not on the hook to cover the tenant utilities?

Is the one tenant covering the entire rent or just their half?

It's not a deal breaker, but the discount should be enough to cover tenting, as well as wood and drywall replacement if needed. 

If it makes a good mid term rental, maybe you can find a way to increase rents enough to cover your costs.