One such comparison site after calling me for the list of issues I care about gave these 4 prop management system recomendations. 

That is a legal matter, but still has "accounting" elements in it since something such as co-mingling funds will pierce your corporate veil. 

I don’t think 1031 exchange on a primary is legal 

However, it is important to consult with a legal professional or tax advisor to ensure that this arrangement is feasible and complies with all applicable laws and regulations.

No issues. 

How do you know if you'll be legally allowed to convert a detached garage into living space or create any other type of square footage increase: attached garage conversion, basement or attic conversion, ADU, etc.

So, buried in this is a more important issue. 

Supply chain issues seem to have largely normalized.

The issue is the building has a special assessment on it where 25k is paid this year (by the seller) and another 25k will need to be paid in the near future tbd (by the buyer).

I do BRRRR not flips but the same issue applies when doing multiple things at once.