I don't think anyone would "normally"
paint a sail.
Either
(a) Get it made out of a high visibility colour (flouro pink is good), or
(b) Get it made out of standard dacron, and have your
sailmaker stick a large high vis patch on both sides.
Incidentally, dacron is generally the way to go. Kevlar / carbon are not recommended for storm
sails.
I agree with the previous poster who said that high cut is the way to go.
Some storm
sails have a full-hoist bolt
rope, even though the
head of the sail is only 1/2 to 2/3 hoist (maybe to stop the
halyard slapping on the forestay?) If you do have a bolt
rope and foil feeder system, you should have eyelets fitted into the luff so that the sail can be shackled onto the forestay if necessary (extreme winds tend to pull sails out of feeders). It is also a good idea to have
sheets permanently fitted to the clew for ease of hoisting.