The only fly in your ointment is that your 1031 money to him for a 50% tic interest in the property constitutes a sale of real estate by him. 

Mj Mckinley I'd suggest learning what constitutes a "deal" and how to structure a deal first.

I'd suggest starting out by analyzing properties and learning what constitutes a "deal"  there are alot of pigs out there with lip stick but underneath the lip stick they are still pigs.  

Courts have ruled that the Act may require a housing provider to grant a reasonableaccommodation that involves costs, so long as the reasonable accommodation does not pose an undue financial and administrative burden and the requested accommodation does not constitute a fundamental alteration of the provider’s operations.

Just because you spent some money exploring opportunities in the state does not constitute business activity, so I think your fine, I agree with @Scott McCadden that I would set up an LLC in Texas if you do end up purchasing a property, or may want to explore using a land trust to hold th property which may avoid this issue all together, this has become popular in FL, but not sure if they work similar in TX.Hope this helps good luck

I'm not really sure where to draw the line in terms of what constitutes operating the business.  

I asked my attorney what constitutes a rooming house?

Although duplexes are doable, and there is opportunity there, by definition duplexes are located in rental areas, which often do not constitute "the best neighborhood."

Also if you close lets say a month or two earlier doesn't that constitute mortgage/tax/insurance/utilities savings or at the very least opportunity cost for other ventures?

I dont think that additional costs such as legal fees, interest etc constituted the difference. maybe 2nd and 3rd consolidated ?