An 100% Chameleon ring is non-existent. If you mean a wardrobe of Chameleon gear, then yes, you can achieve that. However, it is literally the most broken thing one can do in Oblivion, as no one can see you. It is like casting Invisibility, except you can still attack and whatnot. Closely following that are reflect damage + resist magic/spell absorption/reflect spell. You only die to poison and arrows in regular fights. I did it once, and it was too easy. I don't play that file anymore. Though I agree, magic is one of the easiest ways to play the game.
Horse riding is a bit hard in Oblivion, and apparently they're making it smoother in Skyrim. However, I don't see the appeal of fighting on the back of one. It'll just be harder for you to hit them if you're not using a weapon with decent range, and most horses are weak as hell anyway, so they'll just get taken down. Oh, side note, doomstones are returning, and they change the character's birthsign, as opposed to just adding an extra greater power like in Oblivion.
Monster scaling seemed alright to me. The game would've been way too easy if the enemies weren't stronger. But the dungeons in Skyrim apparently level lock once you enter it (meaning if you go in at level 1, all enemies will always be level 1 enemies), so maybe you'll like that. Don't quote me on that though until I remember where I read it, lol.