Check this aa.com DFW International Airport at a Glance page for a visual of how the terminals are situated, including the TrAAin and moving sidewalks connecting the terminals. 1.5 hours should be perfectly fine - in fact, that is considered a leisurely transfer there!

MD80s are reliable workhorses, being reconfigured to add a row of the two that were removed from coach for "MRTC" - so it looks like there will be greater seat pitch in the exit rows and forward (forward of row 21, but seats 19A and F have no recline.) Seats are AB - aisle - DEF in coach; the farther forward, the more comfortable, generally - from 26 aft, noisier, more crowded, etc. (in the 30's, the engine is right outisde.)

You can check where the flights are arriving and departing approximately by using the "Gates, Times, Status" box on the home page.