Two or three times during play I've gotten a message about copying an item to clipboard to help the game developers. Does Steam automatically collect that data? If not, do we need to send it to you guys? Or is not important enough to bother with?

Steam does not collect the data, you can email rob at rob@longbowgames.com or post the problem here as well

I was searching for a thread to put those errors in - this looks like the closest thing.

Loading game: Resources/Campaigns/caesar default.fi
Error: Cannot create trade route
Stack trace:
[C]:-1
[string "QuestBibracte.SupplyRun"]:24

Got around the bug by building a fort at the mountain near Bibracte and making a line through it.

And my first crash (dump here):
http://rghost.ru/52961475