The heat pump will be more efficient than electric heat, and not susceptible to variations in fuel prices.  

Performing some variation of a live-in-flip is certainly the way to go when you start out.

This could be a variation on the current con game of someone leasing out a vacant house that doesn't belong to them, especially at a sub-market price that blinds victims to the red flags.

Extreme variations from HUD can be challenged.

I know there is the possibility of size variations between manufacturers; are there ways to adjust for minor size differences when setting on a perimeter foundation?

You can do it via BP search feature by looking through old posts where the variation of your question has been asked many times in the past.  

your options are to ask a property management company, maybe ask a realtor, look yourself on zillow or one of the many rental listing sites for comparable properties, or use websites like rentometer or another variation.

Most brokerages will have some variation of an MLS integrated website that you can use.

I don't think the rental zestimates are very accurate because their can be large variations between assets.

Similarly, just over 16 percent of the U.S. population and 23 percent of the poverty population is Hispanic, but nearly 40 percent of the total population living in communities of concentrated poverty is Hispanic.Regional variation in the racial composition of these areas is most dramatic for Hispanic and black populations.