1. Applications for next season won't be available until December/January, but send it in as soon as possible. Starting in June isn't unusual, but it will help if your contract is as long as possible - the longer you can work (until August, September, whatever) the more likely it is that you will be hired. Applications will be available by visiting the official website (there will be a request form) or calling 1-800-668-JOBS. From Hawaii, I'd wait 3-4 weeks before calling in, since it will certainly take longer for them to receive your application.
2. Yes, when you interview over the phone you'll be able to request a location, and they really do try to grant that, since they want to make sure that you'll accept the job! If you were requesting Raptor or MF or some other very popular location, it would be more difficult (they'll give those to employees with experience first), but it's always worth a shot since not everyone returns from year to year.
3. To be selected: Have your employment dates as long as possible, and be sure to indicate on the job application (there will be spaces to do this) that you will accept any job in given departments. That shows that you're willing to accept things other than your first choice, because you really want to work there. And call and talk to them (frequently if necessary!) to demonstrate your seriousness and interest - especially from Hawaii, you want to be sure that they know you're able to travel the distance and so forth.
4. CP will give you uniforms and you don't even have to launder them, just exchange them for the identical size, no problem there. They will also provide your nametag/ID badge, which is your key to everything! As for what to bring with you, when you receive a contract you'll get a suggestion sheet with tips on it, but don't forget your birth certificate/social security card and identification like that so that you can process in, an alarm clock is a must, you may want to bring your own sheets since what they provide may not fit all that well, a couple changes of clothes but not too much since you'll be working a lot, etc.
Most of all, have fun! :)
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PO!NT OF VIEW - A Different Look at Roller Coasters
http://www.crosswinds.net/~justmayntz/thrills/