If I function as the syndicator including acquisition, operation (with a separate management company) and disposition (whenever that is), what is fair in terms of dividing the monthly cash flows?

Though move ins could slow as people aren’t doing or buying much of anything it is at least going to remain a functioning business even in a downed economy. 

However, as my portfolio has grown, ResNexus does not offer the functionality that I need to scale.

Once you have a short list, get an account with each one and run them through the wringer to see how they really function.

Multiple recent studies supported that they remain relevant and practically functional in the Orlando property management market today.

Be advised, though: Some seller financing offers may function more like rental agreements than traditional mortgages, and offer unfavorable loan terms that offset any initial benefits to be had.

As for your principal residence, it sounds like you are in a "Functional Obsolescence" issue. 

I would make sure it is clear that it is for the gas, and then anything that is not functional that could not be tested because the gas was off.

I come from a more institutional level background (most of my career has been selling land to the national homebuilders), so I understand the mentality and how the larger companies like AmericanHomes4Rent, Invitation Homes, et al function.

Functionally, it feels like we live in one unit of a duplex, but it is technically still a SFH.