All of Horus' powers are borrowed from other deities for now, so they're quite limited in comparison to wait real elemental gods can do. Horus has a bit of control over the wind but he can't control the wind at the same level that Seth can control the sand, because Horus is not actually the god of wind (moreover, he's not even a god yet) while Seth IS a god and the god of the sand/desert.
No, sorry. There's no info of that on the story (that I know of). But being a god is not a question of just reachng a certain age, though (if that's the reason you're asking) Age is not the reason neither Horus nor Anubis have become gods yet. Thoth (the god of knowlege) say that they have to have both a perfect mind and body in order to be able to become gods (aside from already having both a god father and a goddess mother, of course). Both Horus and Anubis used to have a stunted physical growth (which meant an imperfect body) and emotional issues (that meant an inmperfect mind). Horus overcame the stunted growth thing, but he said he's very much aware of the emotional issues making his mind stay too "imperfect" to become a god yet.
doesn't it makes it easier for horus as he controls wind which can be used to control sand in the desert, making it a lot easier for him to defeat Seth??
but this boi is just whipped and doesn't want to defeat him