Variety of braces exist in  dental Market....if u want go for invisible braces....instead u can opt for re-aligners( expensive but comfortable option )

Yes but cost is too high for clear one

Yes there are brands,Demon is the most clear braces ,it is transparent and wire is a thin copper wire,so we can't make out,but relatively cost also higher, consult your orthodontist.

yes, both types exist. there are various brands for braces just like we have various brands for the phones you buy. they serve the same function, but some are more superior than others. of course, for the very clear braces, the cost is higher. as for invisible braces (where the braces and wires are not seen at all) the cost is much higher than that