The ones most commonly used are the warmblood breeds, thoroughbreds, irish sport horses, in ponies yes connemaras are known for jumping. At the lower levels you could jump anything really.
Depends more on the horse than the breed
I like Connemaras, they have a level head and if you buy from Ireland they most likely have been ridden there which makes them even braver!
Hanoverians make excellent jumpers. I personally jump an Arabian.
Warm bloods and thoroughbreds but almost all breeds are capable of jumping
warmbloods make nice jumpers. i personally like westphalians.
It really depends on the horse, but you will see mostly warmbloods in the higher levels!