This paywall takes advantage of a natural human psychological emotion called the Sunk Cost Fallacy. 

I upgraded the heating system to natural gas furnaces.

Also, how to tell the tenants/ask them to tidy up for the appraisal without spooking them that the house is being sold or something of that nature?

I found this on Google:New York law provides that “[n]o natural person shall ask or receive, directly or indirectly, compensation . . . for preparing deeds, mortgages, assignments, discharges, leases or any other instruments affecting real estate . . . unless he has been regularly admitted to practice, as an attorney or counselor, in the courts of record in the state” (N.Y.

By doing renovations, you'll be forcing appreciation, along with naturally occurring appreciation through market increases.

Well, then there is the passive versus active nature of the investment as well.  

I have pretty much decided to do most work myself.May I ask, what is the nature of work needed?

Natural gas runs to our street and Unitil will run the line to the house free of charge.

It is a long play to hope for the old steel plant to be revitalized.

The housing development could have a positive or negative effect depending on the nature of the tenants.