As long as you're doing your best job and following proper ethics in your respective field, you should be fine and also have to realize that you can't control the actions people take and the way others run their show.

It's generally more difficult to find such properties and likely will require more work than properties where the distress is in the property itself.It also doesn't matter where the money comes from to make what you said work so long as it's generally available once refunded so it can be a JV partner, cash, a credit line, etc. 

I am thinking I could find a new rental under the $250K range in the Boston or Providence Metropolitan areas right now (as long as the deal is right of course).

You will defer all tax on gain and depreciation recapture from the sale of the Houston property as long as the purchase price of the investment side of the investment portion of the duplex is at least as much as the net sale price of Houston and you use all proceeds from the sale in the purchase.4.

Assuming it is listed in the lease: If they are roommates, it is up to them to sort out as long as it is paid. 

If not, a possible option would be for them to do a seller financed sale - that way they'd still be getting monthly income, plus interest, for as long as the buyer is paying off the property. 

@Jacob HumistonAs long as it won't cause any issues in your relationship, would be a good idea to rent out the other bedroom as well which I can only assume would being in an additional $550-$650 per month depending on the area, amenities etc.

As long as you purchase at least as much as your net sale and use all of the proceeds from the sale in the next purchase or purchases you will defer all tax and depreciation recapture.   

Meaning as long as you live there for 2 years you could rent it for the next 2-3 and then sell.4. 

The Purchase agreement is standard and my assign agreement, if I'm not mistaken, is not really a concrn of the agent, as long as the money is there.... correct?