Sometimes getting involved for a few years makes you realize you don't like it.

While the traditional approach involves buying a multi family property, living in one unit and renting out the other - with rising prices and interest rates; others have considered renting out bedrooms as unit spaces. 

You mention not a fan of landlording, great, the bank never get's involved in that stuff right. 

People who are involved in anything tend to have an overinflated sense of self, ego and importance.

Yes you can get in without "military" involvement. 

For your first question, writing a scope of work (SOW) involves detailing all the tasks and materials needed for your project.

Add to that the fact that private financing typically involves way less bureaucracy, with reduced paperwork and fewer hoops to jump through.

We have several subcontractors that handle the process but the owner has zero involvement.

The apt is on the 2nd floor and the furnace is in the attic.I will talk to the heating contractor about setting up a floor temp ( might involve installing a 2nd t-stat as a couple people suggested).

Now, if they don't want to do that for whatever reason and don't have anybody to work with who would do that for you, I'd have to agree with you that they'd better invest at home rather than getting involved in something they don't understand.