So I'm interested in coding drivers for some hardware but have not decided exactly what to do. I just want some ideas on what type of driver I could write as a beginner. Where would I start? How long would / should a project like this last?
Why would you want to if the manufacturer supplies signed drivers? - nobody is going to know their own hardware more than the people that designed and developed it.
Anyway, you would need the Windows Driver Kit (WDK) if your OS is Windows, not sure about the likes of Linux.
As far as time-scales, no idea.. that depends on your skills amongst other things.