I'am not sure, but here is an educated guess. If the worm end was towards the muzzle cannoneers might get caught on it while working around the gun. Another reason may be that if you put the staff end under the trail it would not contact the rammer stop properly. I don't know if that is why they did it the way they did, but in storing a worm on my gun experience has led me to the above reasons.
Paint everything. Iron black, wood green.
Don't worry about the questions, if you don't ask you don't learn.