Hello, I'd like to make a few mods (notably a control re-map for H-pattern shifters when on a sequential gearbox, and playing around with implementing paint scratches), but I have no idea what variables/functions exists and what they do in order to have any idea how to mod the game. Does a library exists where I can study these things, or is it just a matter of "dig through game files and figure it out yourself"?
Cannot answer exactly to your question, but this bit is very possible there. Most of the game .lua files can be easily inspected. You can find them in the lua folder in the game's directory.