Its ok if all the horses are not being ridden, but they will have to be ridden later.
yes you can
you start to canter
you stay still or walking.
There have been many riders killed by horses.
I stay still or walking
depending on the horse... bomb proof school horse: ask him to stand nicely and hop on spooky horse: mount in a quiet area outside of the ring, or ask the other riders to stop and then mount in most cases, you should have the other riders stop their horses, so you can mount
You start to canter in the indoor ring.
horse shows were inveted for riders to show their and their horses skills and acheive higher levels
They choose their best horse that they thing will perform the best for the task on hand.
Horse riders usually say 'back', or 'back boy/girl', if you are on the ground, but if you are riding, then you have to gently pull the reigns alternately, whilst kicking gently, but firmly. Most horses will do this, but you have to be careful, because it can confuse some young horses.
Some horses may not be chosen by a rider because of : slowness, color, or size and ability. However, it may be because of how many horses and riders there are. For instance say there are 10 riders and 14 horses. 4 horses are left behind, probably the the runts of the horses, you know like I described above.
Yes In fact they fought most of their battle of horses Yes In fact they fought most of their battle on horses