(SPOILER)The Japanese text that appears during the scene with the entirely red man says: "It is not good to let them know of our plans, Ansem."

However, the unknown with the red hair is definitely not a keyblade weilder. He uses circular weapons which people have likened to Kunai, but I personally think it may have been just another Nomura invention like the keyblade or gunblade. He is DEFINITELY pyrokinetic though. The blonde guy fighting him may or may not be Sora. Properly speaking, it's not Sora's clothes, but that doesn't mean it ISN'T him. He is known as the dual weilder and we never get a clear shot of his face. The best view you'll get of him is in Another Side Another Story. He is the person weilding two keyblades in that movie. He's also in Deep Dive, but my copy of that movie is horribly low res so I can barely make out anything in it.