My son and I did the steam train tour probably close to 10 years ago. I have a few notes to share...
"The Loop", starting and ending at the same station, takes about 20 minutes.
There are four trains, so, depending on how many they have running on any given day, the trains may run every 20, 10, 7 or 5 minutes.
They do follow the "national rail rules" (not sure of the proper term), even though they do not have to as they are not connected to the national network. That include the long, long, short, long whistle when approaching a crossing that you may be familiar with if you live near trains or ride a commuter railroad, or are just a train buff.
There are signs up in the ground floor of the station that talk about the history of each of the engines. They were all "real" steam engines doing real work before being bought back in the 1960s by Disney. IIRC, some of the engines are approaching or just over 100 years old.
Painted surfaces on the engines are really hot, unpainted surfaces are much hotter.
There is a indentation on at least one of the locomotive where engineers would put a coin. Those coins partially melt and are now fused to the engine (see the unpainted surface comment above). It is crazy hot in the cabs, i don't know how the engineers handle it. They also have the coldest break room on property...
If you are a train buff, it was a great tour if they still do it. Also got a great picture of my son and I on a completely empty Main Street.
One of the "Tips" I give friends going to WDW, use the train as transportation, and not just a ride. When you are walking 9-12 miles a day, you can use the break. A great way to take you back to the front of the park, or from one side to the other.