In NC (and I suspect other states as well) they are very easy to set up, especially after watching a couple YouTube vids. 

Here's a qucik mockup of the garage more matching the house.That foundation, wow, what a mess.If it were mine I would have a structural engineer and maybe a soil engineer come out and give an opinion on it.It's sheer weight may have made it crack off like that, no rebar, etc...If it's was salvageable, maybe I would jackhammer away the broken parts and reset the walls on the good part. making the garage smaller.Disassembling and bracing one wall at a time and increasing the overhang of the roof.Then when done, gypsum board the entire thing inside and paint it ceiling white.If it were  my personal garage I would Pink Panther insulate it and use a space heater for winter comfort.It could be a nice little gym for renter who works out.Also, I would have an electrician verify the electrical is hooked up correctly for garage (because the concrete seems amateurish I suspect the electrical may be too).

I'm "Old School" and I suspect you are in the Mellineal generation.

I suspect with a little effort you would have 4 to 6 relationships with syndicators out of one decent bootcamp class.  

She's the executor but I suspect any decisions will include the 3 beneficiaries. 

It will definitely interfere with the ability to obtain clear, marketable (insured) title but does not, in actuality, prevent the transfer of an interest by deed or other method.If you are starting out, you might use such a list to identify "leads" then vet them for equity to become "suspects."

This room has western exposure with a LOT of windows and tends to get quite warm if the blinds are left open, so I suspect this will be a significant issue.I really appreciate this forum.

There's no logical reason to go through the expense unless you suspect a large amount of construction debris is lodged in the vents.

If things ever do come to that, I suspect I'll just sell everything because I cannot imagine trying to maintain "green" systems in a rental - it's hard enough maintaining systems that have 40 or 50 years of proof behind them, much less think about keeping up with experimental things with a lot of moving parts. 

I need to shop for a whole portfolio insurer, it's one of those "get a round tuit" things, because I suspect I could save some money there, but I do like being able to take care of things in 2 seconds with my agent.