1) I personally don't know any, but they probably just skipped me by.

2)I haven't heard of any glitches. Yet. A million monkeys on a million typewriters, will create shakespeare, eh.

3)It's a cave that starts off filled with Zubats. When you do Mystery Gift, the cave changes and you can catch different pokemon in there, like Mareep and Houndour.

4)Celebi can be obtained only in Japan with a colosseum Pre Order disc. The US ones give you Jirachi.