Any lender worth their salt should be helping to advise you on the property you want to purchase to make sure it is and will produce positive cashflow for the financial stability of you (which in turn assures the note can and will be paid back). 

First of all, you need to seal all the opening of your rented units before using any cockroach killer spray.

They use all the wrong stuff on those.Ceramic Tile on floor because they will burn or destroy linoleum or good floor covering.Inspect your units often and do regrouting/sealing as necessary.

We are going to be redoing the entire electrical, plumbing, and heating systems, so we aren't afraid to move some walls.The hardwood in the living room and bedrooms looks good (isn't cupping or bowing) but I am not sure if I should spend the time sanding and sealing or if another solution is recommended.

I am interested in building modular in the Salt Lake City area.

Seal all vent boots and furnace or water heater vents with a clear elastromeric sealant like Through the Roof....we handle several of these repairs a week in Atlanta through HandyANDY and Through the Roof is good for 20 years....great product.When you seal the boots, run a bead of sealant over the tops of the gasket that slides along the vent pipe.  

You gotta take some of these articles with a grain of salt and just hop in there.

Get the stainless range, take the decent Frigidaire range out, and move it to unit in another building where the range is a non-sealed burner, pilot lit POS I picked up for $50 12 years ago with a bunch of used appliances.

High because of STR and high because of pesky salt water.

Can you shim it and seal it with an expansive caulk?