Hello!
Thanks for the reports.
What exactly do you mean that you can't choose the cars to pull? There should be a dialog box when selecting engines that are capable of hauling cars. Not all engines are though, since many trains are multiple units.
When we're talking about mods, try to deactivate the "only show consists" checkbox, then you'll be able to choose locomotives, followed by cars. Or you can create your own consist files and save them in the consists folder.
Regarding the speed limits, when you're going to fast, you'll derail. So that's not a crash but rather intentional, since trains aren't supposed to go faster than the speed limit. The speed limits have to be adheered to much more strictly than in a car, actually.
I hope this answered your questions.
Regards
Taurus Fan
Viewing post in Transport World Simulator comments
For example, I select a train intended for freight, and the game shows the first additional wagon, named something like 60. I don't want that wagon, so I move down with the arrow key to select another one. When I choose that wagon and click add, and then start the game, the list of wagons shows two that I did not select from the beginning of the list.