I think you've really highlighted the difference between you and I, and that is that you appear to consider America a market, while I see it as thousands of individual markets.

Convert Apartments into condos: You'll need to work with professional team to help you execute on all of the paperwork for this but you can find a duplex, triplex, quadplex, and convert the units into a small condo and sell each unit off individually.

As far as new owners making money you'd have to look at the City's on an individual basis.

Coliving is basically when you rent out individual rooms in a nice home. 

The best course of action will depend on your individual circumstances, investment goals, and risk preferences. :)

Now ideally I could STR all of the units individually but given this is my first foray into STR, I'd like to set up a couple of these units as LTR and try to AirBnB/Vrbo one of them.

I’m in the process of switching several of my buildings over to individually metered propane heaters so the tenants will become responsible for their own heat costs and more accountable in their waste of resources.

Should I go with a company or try to find an individual?   

They want to sell all of them at once, and not piece meal them out individually, so they are asking for less than market value.The offer is 6 homes 5 of which currently have renters, for $400,000.

It's possible that the company that owns a bunch of the units retained the right to control the the HOA until they are done selling.Simplest answer is to ask the seller who controls the HOA and if not the individual owners, when will it be turned over to them?