The only concern is that, being a newly formed LLC, there is nothing to go after.

I am new to all of this, and I have really good tenants, which may be causing a false sense of security.

To give solid advice the community will likely need more information, (where you want the vacation rental, how much you think you want to pay, any questions/ concerns you have) It is difficult to give advice with no supporting information. 

What are major concerns for the decision; and how many started out flipping their primary residence and rehabbing while living there?

If your agent showed you the property and/or submitted an offer for you he already has procuring cause and will be entitled to his share of the commission regardless of what happens next. 

Using a lockpick is less of a crime and if you cause no trouble or damage - you are only on the hook for having the lockpick which is illegal equipment.

.  :(  It just says that they are responsible for the damage that they cause.

I get why some would say investors are causing the affordability issue, but my guess is it would be a lot more productive if policies/discussions focused on two issues, (i) why haven't wages been increasing as asset prices and rent have gone up the last 10 years and (ii) why isn't there enough of an incentive for investors to build affordable housing.

The delays you mention seem excessive, that said, if the delays are due to the local utility company (some are common but not that long) then you don’t have a lot of options but I am feeling like the contractor here has caused at least some of the delays.

You have to know the buildings which are friendly to STR as far building management is concern.