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.
Probably whatever good horses they could get their hands on. Many of the American horse breeds today werenât so much breeds then as they were types. Likely the horses used would be tractable, trainable animals with good stamina. That way an not-so-skilled rider wouldnât have much trouble.