It will feel like some one is pushing on your teeth. The brackets stick out a bit from your teeth making it feel like you have a full mouth of metal, big lips and your bracket may rub against your lips feeling again like a metal file.
While some breeds may be more suitable than others for a beginner rider, there are always exceptions to the rule. Quarter Horses often make great beginner horses because of their even temperament, but some can be quite hot or energetic for a beginner.
Weanling. Best breed for beginner is a school horse :) it's really important for you and horse that you'll have once, to go through some ride lessons, so you will do less mistakes and your horse will obey you and you will be happy about him. Read a lot about horses and taking care of them and ask a lot of questions.