Legally, I doubt you could make a case for not renting to him or her on the basis of their chosen profession.

Just want to make sure everything is legal and I have necessary out clauses. 

Is it legal for me to purchase the place with the intent to add no value and sell it to another potential buyer to save them money and make some profit (15% markup vs 30% realtor commission for example.)The place is a commercial property currrently being sold for value with equipment and furnishings coming with it for free.

I work as a legal secretary and want to support my "art habit" (as well as my retirement) by holding onto rental properties, and probably living in one of them in a few years.  

If there's anything of value in the unit tread lightly until you have legal possession otherwise you can get yourself in trouble. 

Contamination issues are the legal responsibility of the current property owner regardless of who caused them.

Additionally, he is fighting the sale of the property and claiming he is the legal owner. 

Also, you must stay at that residence for a minimum of 1 year I think before moving out.I you apply for a conventional loan and do not intend to live in the house, you must apply for a second/investment home instead of a primary residence.Since your duplex is fully occupied I'm not sure if the bank will require at least one vacant unit prior to closing, but they will at a minimum want you to LEGALLY sign that you intend to move in within 60 days.

I enrolled in the real estate program only to find out more about the business legal aspects so that I wouldn't get caught up with the laws and regulations.

You are welcome to contact me for legal advice, setting up LLCs, drafting deeds, title research, etc.