BRRRR is the way to go.Additionally, a good Turnkey company will walk you through the purchase and Closing process, show you the rehab, connect with your Lender, Title company, as well as either directly lease and manage the property in-house or arrange for such.

However this doesn't take into account the search, analysis, arrangement of PM, etc.

I call my mom and arrange for her to watch my boys (twin 3 year olds) over labor day weekend while my husband and I get the place cleaned out, painted, and carpet out and ready for the flooring. 

Also, in a small multifamily you are more likely going to need to arrange some sort of lawn care since the odds of a tenant taking this on are less likely. 

I would definitely suggest you take a lot of pics when you see the property or if you have enough time arrange for a contractor to come with you so he can walk the property and talk to you about what repairs are needed.

How is a deal such as this structured; what parties are involved in this type of arrangement; what costs are associated; are there specific covenants or terms that need to be included in the contract; etc?

I would come to a good arrangement with her and be fair with her situation as it's not her fault. 

This type of thing can absolutely be done as a TIC arrangement with him purchasing X% and you or your LLC taking title to the other TIC %. 

Read all you can about owner financing, especially the legal aspects of it in your location.Learn how to locate and negotiate these types of arrangements, so you get very comfortable with the language and how they are structured.

The strange history of this property indicates a greater chance, though still not likely, that you'd be able to arrange a purchase or a rental with Citi.