It’s sort of up to the dev that made the code. There’s no hard and fast rules, although there are forum categories to try to keep things somewhat organized.
Let’s start with, where did you find the driver code that you edited? Shouldn’t be difficult to determine which dev wrote it, and from there, whether the dev has an active thread here in the community.
Not really. There are a couple threads that are kept as wiki posts so that anyone can edit them. But they’re only as accurate/up to date as users like you and me want to maintain them. There’s one for device drivers and one for apps.