Well, if you prepaid for Colosseum, you should have received the bonus disk. Where did you prepay for Colosseum at? Perhaps you should call the store that you purchased Colosseum at or e-mail them if you purchased online, and ask them why you didn't receive the bonus disk. The bonus disk is the only way to get Jirachi without using a cheating device. If calling/e-mailing the place that you purchased Colosseum from doesn't help, try calling different places around your house that sell video games, maybe some of them will have some of the bonus disks left over. If all else fails, try eBay.
Deoxys is a Pokémon that is found on the 9th island in Fire Red/Leaf Green. However, there is no current way to get to the 9th Island, because getting to it requires the Aurora Ticket, and there is no way to get an Aurora Ticket in Fire Red/Leaf Green. The best bet is that Nintendo will have promos that will allow people to get Aurora Tickets and Mystery Tickets, kind of like how they did the Eon Tickets for Ruby/Sapphire. (Mystery Tickets are required to get to the 8th Island, and catch Ho-oh and Lugia) Deoxys is an interesting Pokémon unlike any other Pokémon. It has 3 different forms, depending on which game it is currently on. Whenever the Deoxys is traded to another game, it will change it's form depending on what game it is on. When on Fire Red, Deoxys will get higher Attack and Special Attack stats at each level up. When it is on Leaf Green, it will gain higher Defense and Special Defense stats. When it is on Ruby/Sapphire, it will be more balanced, somewhere between the Fire Red/Leaf Green, although it will be more offensive based, a little closer related to the Fire Red version than the Leaf Green version. The version that Deoxys is on when it levels up can also cause it to learn different moves at certain level-ups.