It's unfortunate to hear you've shelved it for the time being. I've been looking into building one for myself. What direction would I need to go to get started? Would love to hear about your experience with the project.
Everything I learned about quadcopters I learned from the internet. Most of the links that I learned about quadcopters from came from the various quadcopter, multirotor, and drone subreddits. I usually forget a lot of stuff I don't actively mess with, so I've forgotten most everything about quadcopters.
That document I linked in the original post of this thread has some more information about quadcopter parts. You could take a gander at that.