Is their credit report good/clean?

Put the new furnace next to it, and have the HVAC tech swap over the electric, gas/oil pipe, flue pipe, and water lines or ducts (use flex duct rather than having sheet metal bent).  

Does anyone know if I must (by law) give notice to my tenants to do things like mow the lawn or clean out the gutters?

There is no guarantee that the next tenants will be better or get along better.Examples:Operation, Maintenance, Storage, Alterations to Premises: On a continuing basis, tenant agrees to: Keep premises in a clean, neat, and sanitary condition; no parking, storage, or accumulation of debris on lawn or yard.Not store non-operating vehicles, nor boats, RV’s, motor cycles, trailers, firearms, equipment, tools, hazardous materials, liquids, paints, fuels/oils or chemicals on premises without landlord/agent approval; no waterbeds

The unit just needs cleaning, painting, and a few repairs.

No matter where, when, or what, each will require a good cleaning, and basic maintenance check.

If the units are non-smoking and you have to clean the units in a manner to remove smoking odors and stains, then by all means keep the deposit. 

This is what we have decided for the scope of work on the rehab:Professional mold remediation with basement clean-up ($4600)Conversion of the family room on the 1st level to a 4th bedroom. ???

I was wondering if anyone had experience with them and would be willing to share (*ahem) some strategies.I'm also unclear on what needs to happen after a purchase to clean up the title and ensure there are not other liens... 

Credit probably needs about 3-4 months to clean up.