@user108407 best of luck with the project, don't forget us when you make your first million!
3) On longer rides, yes, a saddle bag. My main cycling is short distances (10 mile commute) and I prefer to travel light without kit
4) The zip on my saddle bag feels poorly designed, it never seems to open on the first attempt
8) Colour, black. Shape, subtle
9) A quick release mechanism may be useful