The Cardinal is usually taking Amfleet I and II coaches and viewliner sleeping cars. Occasionally a Heritage car will be in the consist, but most of the time they are making the run 'dead' from the Beech Grove shops up to Chicago.
Regarding the trip report....it was great! While I've never ridden coach overnight with a youngster (I've always book a roomette), my experience with my then five-year-old son was almost mirror that of your daughter. And on the next trip we took, my son was then showing my wife how to operate the doors, where the trash, the restrooms were located. They pick up and retain everything they see and hear.
Also, one reason that the locomotives stay running after the train has arrived at its desitination is that diesel (or in this case, diesel-electric) engines are actually very efficient while they idle. Adding to this, they can be very stubborn to re-start when the engines are 'hot'. Also, not long after you have departed, the train will be pulled away to be refitted for its next journey, so it won't be staying under the trainshed for long. I'm sure there is an 'expert' who can validate or correct this theory.
It was also nice to read your descriptions of the station(s) from which your journey began. I wish I had such a facility to depart from. Unfortunately, the closest 'station' to my house is Crawfordsville, IN, and we leave from one of the plexiglass 'huts' with an Amtrak sign hanging from the roof.
http://snow.prohosting.com/usarail/crawfordsville.htm
I can report that the rather run-down station in the background has been slightly upgraded and is currently being used as a physical therapy center. Unfortunately, the tenants aren't railfans and have posted several signs on the property saying 'no parking for trains' and 'restrooms for patients only'.
I don't know that I could handle the length-trip that you took in coach, but it was great reading. Thanks!