They don't have to if they're not being used to pull carts on rough or hard surfaces like roads. If they're out in a pasture all the time and not being used extensively, then no they don't have to.
Horses wear horse shoes on the bottom of their hoofs.
By mustangs I assume you mean wild horses. No, only domesticated horses SOMETIMES wear horse shoes; it is not a requirement that they wear shoes. Two of my horses do not wear shoes and the other one only wears them on his front feet for orthopedic reasons.
I work with miniature horses and they pretty much act lik normal sized horses
no
Barbara Naviaux has written: 'Miniature horses' -- subject- s -: Horses, Miniature horses
This is no more dangerous than if the horse is barefoot.
Of course miniature horses can get pregnant. Horses are born, not made. And they're born from other horses. Only way for that to happen is if horses get pregnant.
If you meant 'why do riders wear boots?', then I'm fairly certain you can answer that yourself. It is the same reason you were shoes: we wear shoes to protect our feet. If you meant 'why do the horses wear boots?', then the answer is, again, to protect their legs.
That's depending on the horse, the size can vary.
Miniature means very, very small, but generally in comparison to the 'natural' or 'common' size. It does not have a specific size connotation. For example, you have horses and miniature horses, as well as poodles (standard poodles) and miniature poodles. The miniature version of each is much smaller than the regular version, but the miniature horses and the standard poodles are comparable in size.
NO!!
very!