It was also a learning experience for me that someone could do everything correct and have external circumstances do you in.

In trying to answer that question, without going into the political side of things that have been injected here, I would answer that all bubbles not matter how they are created (in this case by the government stimulus) will at some time burst and that the govt role is to protect us from external foe (thus the wars) but not to protect us from ourselves.

Stockholders are anonymous, so if there's no public recorded record, sell your properties to your LLC, and like magic they hide Maybe so, but I'm much more concerned about risks created by the real estate than risks created externally that I have some control over.

What type of external threats could hamper growth?

One could keep the external historic charm, but modernize the internal layout.It would be a shame to see it sit empty - but this time, unloved - for another decade, but I do not readily see a profitable way to save it.

The positive is that the HOA may take care of alot of the external maintenance issues for you with the HOA fees and I feel that condos are easier to self manage with tenants cause not as many moving parts.

It is quite common for the LLC veal to be pierced by either internal or external lawsuits. 

What type of construction are you planning - minimum stick built with 1-2" of XPS externally (R28 - R33); 2x8 (or nordic framing) walls with 2-3" of external XPS for a {near} R50 wall; SIPS, etc.?

I do like the advantages of a condo in that the building handles all external costs and maintenance.

No doubt there will be some internal and/or external common areas to be built too.