I've had this game for a while and just started replaying it (i got tired with it since I already beat the American one). I'm up to right before macalania when you fight brother's machina. Its kinda hard this time around though. Can we make a list of the different things in International?

Obviously theres the new sphere grid and dark aeons but i heard something about taking chocobos on the airship. Anything else?

There's a chocobo on the airship in X-2, not in International. International's exclusive features (apart from what you've mentioned) are the Power/Mana/Speed/Ability Extract and Full Break abilities which weren't available in the US and original Japanese release, and the Magus Sisters, Anima and Auron's Overdrives all do more hits.

That's all I could think of...

All I can think of is the Dark Aeons and the new sphere grid.......erm wasn't playable Blitz included?