I think you are looking at the wrong places, insulating the floor wouldn't change much. 

If you make them and insulate them good, it will be ok. 

Insulation paint.

hi all i am a new landlord and got my first rental property. tenants moved in in September and October. the first month was fine but when December hit it got extremely cold and the heating is electric. due to poor insulation in the home that we did not know about the heat has to be turned very high up to keep the home warm, however since everything is electric it is causing the electric bill to be $800. the utilities are the tenants responsibility. however because of this one of the tenants has been extremely non compliant with paying rent.

Are there any guidelines or best practices (ie: rewiring such a property would be more valuable than updating insulation).Is it something you need to ask the insurance company about to get, or is all this determined in the initial interview with the potential insurer?

Yes it's a huge problem.You should fix this correctly now.Open the walls and put in proper sound reducing insulation.

However to save money when she had the house built, she left the basement unfinished--it is just studs, insulation, and windows/doors, plus plumbing in the foundation.

I was thinking that the very thin hard carpet could serve as a sound insulation layer, and just installing click together LVP right over the thin carpet and the thin hard stick on tiles. 

Each of the 5 warehouses on this campus will require updates (construction of offices/bathrooms, roof repairs, paint, siding repairs, new penetrations for doors, updates to electrical, insulation, and extension of water and sewer). 

Also, if it's Lennar, be prepared for problems, insulation issues and therefore paper thin walls.