Sorry, I again missed a question as a new discussion (it doesn't create a notification).

Fittings and wagon parts are resources from Discrepancy. We added them here for compatibility reasons but they actually should not appear without his mods. That's a kind of bug and you can just ignore them if you don't use DS mods.

Money is a part of the North and used as currency in late game. Some merchants attracted by the big trading post want to buy resources and pay a high prize in coins. Others want to sell stuff and accept money, which has always a stable value. Resources don't have. Money is also useful to create stocks, especially stored in the bank where it is save from loss.