Sol Invictus
Erudite
Most of the weapons in the game would be rendered useless if there was any horse combat. You can't fight a mounted horseman with a dagger, axe or even a longsword. You'd need a halberd, zweihander or a pike. Oblivion isn't that kind of game.
It can be, but that's up to the modders.
It can be, but that's up to the modders.