It depends have you only rides lessons horse that are already trained or have you ridden horses that say might spook easily or are stubborn
Yes as long as you keep up with the training and work hard yes
Possibly! It depends on what you've done in those 13 years. 13 years riding well schooled horses, or riding school horses is very different from 13 years riding young horses. If it's your first time schooling a green horse, I would highly recommend getting help from someone who has experience bringing on young horses and I would say that regardless of how many years you've been riding. It's a critical time to set good foundations for the horse's future career.
Depends, if the rider is willing and fearless then without a doubt