There are several of our members that Live in the DFW Area and know all the Details about Union station, One of them, saxman, even works as a Volunteer Station Aide when he's not off Flying Planes or Riding Trains! (Hes an Airline Pilot by trade!)Until one of them weighs in, Ive been in this Station many Times while riding the Texas Eagles so will attempt to answer Some of your Inquiries!
The Agent @ Union Station Loads/Unloads Bags on the Eagles. There are DART Light Rail Trains, TRE (to/from Ft. Worth)Trains and the Two Eagles that use this Station plus Many Freights! (The UP Line runs through Arlington to Ft. Worth past Cowboy Stadium, Six Flags and the texas Ranger Ball Park and BNSF goes Via Irving (same as the TRE Trains ) towards Ft. Worth and Points West! The Amtrak part of the Station is the Ground Level/Basement (for Blacks back in the Bad Old Seg Days) with Wolfgang Puck Catering occupying the Upstairs, which is Closed to the Public, where the Plush Passenger Waiting Room (White ) used to be in the Segregation Days!
You can Day Check your Luggage with the Amtrak Agent in the Waiting Room for the New $4 per Piece Fee that Amtrak has just put into place! Its' only 2 Blocks to Dealy Plaza and the JFK Book Depository Musuem and theres a Pretty Good Deli next to the station, think it's Cindys Deli! Day Passes for DART and TRE are a good Deal and if you go out to Mckinney Avenue on DART (City Center Underground Station) there are old Timey Street Cars and Upscale Shopping Stores and Eateries and Bistros!
The West End Entertainment District is also close to Union Station and you can ride DART there or even walk, it's only a few blocks! When we had our Mini-Gathering in DFW Last Jan., we did lots of these activities but in all Honesty Ft. Worth has more to see for Tourists than Dallas in my Opinion! YMMV