1. Check out this gear tutorial:
http://supercoldmilk.com/ac3dtut/beginner/gear.html
You can use the same principle of revolving a line to make a wagon wheel --- you'd make one "section" of the wheel, replicate it around, snap/optimize the vertices, etc.
2. Instead of creating a cylinder, you may want to try revolving a surface as thin as you want your canvas to be around the origin, then getting rid of the lower surfaces.
Hope that helps