A few questions:
Why do you "season" a bag, and with what?
Why does it need to be "moist"?
Why do bagpipes sound awful when you start them up?
What's a drone stopper?
-Penguin
ok. here goes:
1 and 2 tie in together.
seasoning is required to basically airproof the bag so you dont lose even more air when playing. the bag is seasoned with bag seasoning. not even kidding

why the bag needs to be moist... hmmm... think of a leather jacket. when its dry out (weather-wise), there are more cracks in the jacket. when the jackets been out in the rain for a bit, the cracks in the leather are a bit less apparent. kinda how it works for bagpipes.
they sound awful when starting because the beast has been awakened.

its really the drone reeds starting to vibrate and create sound. sort of like when you havent spoken in a while and your voice cracks/dies.
drone stoppers are, in essence, pressure valves for the drone reeds. they fit over the reeds, and do two things:
a) stop the reeds from falling into the bag-- its a PITA to find them and get them out again
b)reduce/remove that gawd-awful noise when starting up
hope that helps!