Well, since you've got the 2000 ITR, you've all ready got the slightly more aggressive intake cam than what came on the 97 and 98 ITR's. If you got the money, I'd go with Toda Spec A's but if you're looking for something that will give some good gains, Skunk2 Stage 1's are nice for the money. With both of those sets you can use the stock Type R valve springs and rockers and all, but most people suggest upgrading those parts if you go with like a Toda Spec B or Skunk2 Stage 2, and in that case, the Toda Spec B and Spec C non-vtec lobes are the same, but the Spec C vtec lobes are more aggressive, so you might as well go with the Spec C's if you planned to upgrade the valve srpings and all anyway.
Also, I'd buy a header and exhaust before I spent money on cams. And yes you need something larger than 2 1/4 because that's what the Type R exhaust is stock. Most aftermarket exhaust are 2.33", but you can find a few that are 2.5". Get the header, exhaust, cams, combined with your current mods, tune it with the VAFC and I'm sure you'll enjoy it. I've got the Apexi World Sport on mine and I love it, not the most powerful exhaust but it sounds stock which is what I wanted, I wanted the quietest exhaust on the market, even if it meant me sacrificing hp.
Good luck.