Well first of all sorry about the ADHD. thats going to make things tough. I used to always have good ideas but then id forget exactly how I played them. So, I got a littlle 4-track recorder about $100. When I'd play i turned it on. There were my ideas right on tape. Try it. As for the songwriting process there is no right way just the way that is best for you. If you don't feel comfortable being a lone writer tell your mates. Me and my band members found the best song writing stratagy was when one person had an Idea the others just went with it and found a groove we've all had our little brainchilds that went from a three chord progression into a very decent song. So I say have everyone express themselves. As for reading music it not really nessacary to be able to read. I can but somehow I really don't apply it often if at all. Its best to lern harmonys and melodies. Learn how to stay in key. and keep up with the beat. Its harder than it sounds for some but practice practice practice. Your ear will tell you what bassline goes with what progression, and drumline.