They're basically shooting themselves in the foot.

Basically, it took Mexico 40 years to achieve what took several times longer in Florida.

I've been told by the insurance companies/brokers that a basic Homeowner's or even a commercial policy will not do.

The AC/heat is out? 

It takes actual thought and a programmer's mind to be able to build a CRM into something that's actually effective (sure a basic person could setup a phased text message or email automation, but it's tying everything together with opportunities, automated campaign re-entry/follow-up, social media integrations/automations, etc that is the real value).

ANyway that is  my beginners guide written by a beginner but is basically what i look for.  

And that was my understanding (the basics, at least :-)...Given that, the scenario that Bob presented in Deal 3 above seems unlikely to play out legally...

I think there are two maybe 3 ways to look at this in my mind.  1) you go into it and bring it all up to modern standards but using that old charm to basically take what is there bring it up to modern standards and rent it out essentially I'm thinking cocktail bar or something trendy like that.2) most banks are on really good centrally located real estate if this is true, then I'd consider it for the dirt, plan to scrape the lot and go vertical with whatever the highest and best use is.3) a kind of combo of the two, if the lot is in a good location and its doable, pull the vaults or other "character pieces" out of the building, scrape the lot, and build whatever is best suited for the site there, but incorporate those historical pieces into the final designs.Is the site near a major retail area? 

The day after I set precedence, I gave my info to others who had "illegal" ADUs and a basic "road map" to get themselves legal.  

Basically scale in paper and challenge it with your personal time, resources, desires, finance, insurance, PM, etc.