How create a surface from a non-planar curve?
 

Hi
After projecting a curve on to a cylindrical surface (the letter 'J'), I now want to be able to colour the 'J' differently to the rest of the cylinder.
I found a slow way to do it by duplicating the whole cylinder, then using the trim tool to keep a surface for just the 'J', but wondered if there was an easier way?

Next, from the curve-on-surface of the 'J', I did a Duplicate Surface Curves to create a new curve that I want to use elsewhere, and then scaled it. However I can't find any way of making an independent non-planar curve in to a surface.
Can closed-loop, non-planar curves be used to make a surface?

Thanks

Steve