The fact that you already have multiple units fully rented is a big plus.If I were analyzing this, I’d start by verifying each cottage’s rental history, condition, and potential for adding more units or amenities.

If they don't comply, I believe then the paperwork will be filed with the courts.1) they violated my lease agreement by re-keying the locks and refusing to let me do a walk-through (excuse was she has covid)2) since it's a month to month lease, I can also end the lease and state I will be moving back onto the property and taking it off the rental marketHopefully, these two conditions will hold up in court and will favor me.

You should be within $50- $100 of market rents for long-term tenants with taking into account the condition of the property.

I never make a loan, no matter the equity position, that the past actions of the borrowers lead me to wonder if they will be likely to pay me back. 

PMs have to keep the utilities working for various reasons (uninhabitable living conditions, pipes freezing, etc) and you can't count on a tenant like this to do that.

As others advised, get a structural engineer in there to review the conditions.

You can make minor adjustments based on the type of appliances (dishwasher, clothes washer and dryer, air conditioning, etc.) and the size of the rental.

It goes as follows. 1. usually I let all leads go to voicemail.

Normally when a  property is advertised as "cash only" the property is in poor condition and/or the seller wants to reduce contingencies and opts for a cleaner transaction.

Unfortunately, there are times when being accommodating and making exceptions can lead tenants to take advantage of the situation.