Real modders obviously read the code. Has that ever been any different? The community has figured out quite a lot already, so you have a good chance finding stuff in the forums or simply by asking for it.
This is a good place to start: https://forums.uberent.com/threads/pa-modding-reference-guides-applications-tools.48136/ Much of it hasn't been updated in a while, but a lot of it is still relevant.
