I do think about how epic that would be :)
Yeah, I like your plan. I think you cannot enter a 4 yr old in classes anyway. But you need to find out why your girl is trying to flip over. Horses don't do that for no reason, it is dangerous for them. Maybe her mouth or back are hurting her? I would look into that first, then once that is solved, progress with the mare in dressage (and show her) while still training the gelding until he is a bit older. May even need to wait till he turns 6. I dont' show my horses until they are 6 or older so they are mentally mature. Horses under 6 are still 'children'.
Any gas that has been compressed and then suddenly released can be very cold, so question 1 the answer is that it is very possible. Question2 is depends on the type of extinguisher but probably. Question 3, Depends on the type of extinguisher. Some use chemicals and some just use water or CO2. If it is a chemical type I wouldn't recommend prolonged exposure. Are you trying to be the next Jackass?
