Not as punishment, but as a safety precaution!

Your broker will be able to tell you their policy on commissions.

Flipping is a business, whereas lending and holding rentals are not, and would not have exposure to UBIT.The 401k loan is an emergency safety valve, or a means to tap a little capital to grow a business you may operate personally when other forms of credit may not be available.  

If it was rezoned, chances are they man tell you no and how they were simply waiting for your old house to be sold off and or to become delapitated enough to where they could successfully through Heath and safety laws, force it to be demolished. 

The "perceived" savings are rarely worth the aggravation, and many times they do an incomplete title search, with a title policy that Exempts (section B) unrecorded, but findable liens.

@Steve Vaughan  your a student of the STeven Vaughan scorched earth policy.. .good job understanding that you NEED some MONEY to make Money in real estate.you may want to get a money partner...

I am a broker too; I have abundant capital but have the hardest time finding deals that fit my policy portfolio. 

Anything could happen, I know, but at some point the responsibility for personal safety has to fall back to the tenant. 

In addition to understanding applicable landlord-tenant laws, be sure to thoroughly read through the condominium's governing documents, particularly any policies about renting.  

Just a heads up to check both your Homeowner's policy and Rental Insurance policy to see if you are covered for riot, terrorism, and civil disorder problems.