This house was completely renovated with a new roof down to the mechanicals in the basement and rents for just under the 1% ratio.

Inside each unit they had to cut an opening in the drywall to access the mechanical chase that brought the piping up from the basement into each individual unit.

The Compensation Mechanic is Completely DifferentA Flat Fee MLS listing gives sellers the ability to display a binding offer of commission to buyer agents on the MLS.

However, the mechanics of putting the scenario in effect are far from easy or clear because the title company will have instructions from the lender not to fund unless the borrower provides the down payment in cash, not in a seller financed 2nd lien.  

I did a brief (5 seconds, literally), Google search and found this about USPAP confidentiality:  "It says “[c]onfidential information [is] information that is either…identified by the client as confidential when providing it to an appraiser and that is not available from any other source; or…classified as confidential or private by applicable law or regulation” (ibid; emphasis added).

The listing agent SHOULD tell the seller to make sure appliances, mechanical systems etc are accessible upon walkthrough/inspection day.

A 3rd floor addition will not only have structural modifications, but also require mechanical, electrical and plumbing permits.

Define the scope to what matters (mechanicals, structure, roof). 

Anyone who gives you a number is giving you a rough estimate, emphasis on "rough."

You know the mechanism by which interest is credited, you just won't know exactly what you will get.If you want to know what you will get, then get a whole life policy.