Once the gloss coat has dried, there is no stickiness at all, at least with the brand I've been using (Rustoleum 2x Coverage). It leaves a nice shiny coat that almost looks like plastic.
Yes, I coat both sides of everything. Make sure to let the first side dry completely before flipping them, or they can stick to the surface you paint them on and peel the paper off a bit. Placing them on wax paper should help with that.
The nylon washer does make them easier to rotate, and if they get too free you can squeeze the plastic center piece together to tighten it up a bit. I've had several people comment on how much easier my dials are to rotate (that didn't sound quite the way I intended ...)