These reins are normally between 20-22 feet long. Don't worry, you won't have to figure out what to do with an extra 15 feet of rein.
Some people prefer to wrap the end around the saddle horn for easier access.
This is really a personal preference kind of thing. They look really good on our horses. Horse hair takes some time to get used to. Mecate's are an excellent training device. The release is the reward that the horse is seeking when you ask for something.