Without an EPA certification that soil has been remediate, you can’t get a CO and can’t rent it out.  

Most of the time when a house gets gutted to the skeleton, it's because there was asbestos and it had to be remediated.

To address the current situation it would be worth sending the tenant a lease violation letter with a remediation plan (i.e. pay the additional $50.00 or cut the grass).

I posted a really involved post about my plans to remediate the problem, but I had a bright idea last night that may work. 

He specializes in mold remediation as well

If the sidewalk is heaving up, sometimes (but not always) grinding can remedy those tripping hazards quickly.Good Luck!

If they default, what is your remedy?

A professional inspection is required to determine termites and must be remedied to approve a loan with FHA. did you waive loan contingency? 

This can be telling of how the property will be reviewed once you purchase it, and it can allow for changes to be made early on, if possible, to remedy potential negative situations.

If the landlord, an agent, or other person acting under the landlord's direction or control has unlawfully taken possession of a tenant's personal property the landlord shall be responsible for paying the cost and expenses relating to the removal, storage, or care of the property.Subd. 4.Remedies additional.