As long as the floor boards were useable/fixable, there's nothing wrong with painted and sealed floors.  

As the owner of a rowhouse, over the past yr. we have paid for 2 different pest control co. to come find/seal mice holes and resolve the problem but the problem continues.

Then we would pump it back into the 5s and seal them up..DONE! 

It needs to constantly be sealed. 

There are 3 or so windows with massive seal failure, you can't see through them for all the water on the inside.

If the existing floor is vinyl, the answer should be yes, you can because vinyl provides a good moisture seal. 

The require frequent sealing to enable a serviceable life span and you can't expect a tenant to do that.Use a non-pouros surfaces like title or a newer product called solid laminate (see Homedepot or Lowes).

The license seals all avenues of Real Estate income, you have the ability to sell, even sell back your own fix and flip properties, saving commissions, etc.

Replacement windows DO NOT REMOVE the old frames - - they use a 'Z'bar installation to avoid breaking the existing seal or damaging interior/exterior services.The old glass and it's frame is removed leaving the other casing intact.Go to Home Depot and have someone show you their products.

Finally what works for me as a well as other direct mailers  use full size 81/2 x 11 sheets folded up to fit into an invitation size envelope and don't  seal it.