the certain type of helmet that the horseman (with the blue caparison) is wearing is a helmet with a mask commonly being used by cuman - kipchaks nomads (and probably other nomads like the volga bulgars or the earlier khazars) that lived around the volga river area and the pontic steppe, this certain type of war mask helmet have been found in lipovets, kovali mostly ( or all i think ) founded in nomadic burials, they were also probably worn by the khans or rich warriors or for heavy cavalry uses.
ye
yes that one is more correct, the one in the art looks like an european style kettle helm
yes that one is more correct, the one in the art looks like an european style kettle helm, but we (or i) dont have evidence for the use of kettle helmets to be worn in the middle east
the outermer knight isnt a middle easterner