Has anyone taken TEXRail from Fort Worth (Central Station) to DFW? How was the experience?

For some reason, there is a great BA fare from DFW, and Amtrak between the Austin and DFW areas is really cheap (under $15), so thinking of doing Amtrak-->TEXRail-->BA Flight.
* How is the connection between Amtrak and TEXRail at Fort Worth? I could take Amtrak to Dallas, but it makes a long stop at FTW, and still takes about an hour to make that trip (but I should still have time, if that is easier)
* It appears that TEXRail goes to the very high B area at DFW. Is it possible to walk landside between B and D? I wouldn't mind even going outside. Or are the DFW shuttles the best way?
* This would work on my outbound, but not the return. I'd probably buy a separate one-way AA ticket.