The ideal floor plan that I am looking for would be +3bed / +2bath, 2 car garage, maximum natural lighting, +1800 sq/ft.

Add a few amenities (heat, lights, insulation) and it will cost another $1000.  

If it has lifted shingles, patches etc, in such cases the options are basically; fix it (new roof etc), exclude wind/hail (fire/lighting only), or NOC.

Since I've never lived in my rental houses (and I'm paying abnormally low electrical rates when these are empty...just to keep the frig going, air when showing a place, a few lights, etc.)

They take away the light and the ability to use the window. 

The interior paneling was usually a  3/16 inch photo finished veneer very light weight and the exterior siding was aluminum which was also very lightweight.

Maybe you can shed some light on cost savings as it relates to, retaining 1 part of the original structure (in the event of a teardown-rebuild scenario), where be it, a wall or a prescribed portion of the original structure is retained, per the request of the city/county? 

Maybe someone here who has had a similar experience in their journey can shine some light on the scenario, keeping in mind the following:- I want to do multi-family, probably start with either a duplex or triplex.

I am curious if there is anyone out there, specifically in Ada, OK or surrounding areas that can shed some light on the market, if there are decent property managers out there, etc.

With the landscaping, I typically go for properties with light landscape.