A couple questions about using Mail.app with IMAP/Gmail on my iPhone...

I’m currently using Apple’s Mail program to check two email accounts—one a Gmail POP account, the other a university IMAP account. I’m planning to get an iPhone for Christmas, so ahead of that I’d like to change the Gmail to IMAP—which they recently launched—so that my computer’s Mail program and the iPhone mail program stay on the same page.

First question: if I switch Gmail to using IMAP (presumably by making a change through their Web site, then changing the settings in the Apple Mail program), is there going to be chaos in my computer’s mail program? E.g., will the computer get confused and download every undeleted message as new or something crazy like that? Or delete previously sent messages, etc? Or has the transition to Gmail’s IMAP been pretty smooth for people?

Question two: what’s going to happen when I introduce my iPhone to these two IMAP accounts? Will every undeleted message appear as new (unread) in my iPhone inbox? Will I be able to view messages in my “Sent” folder on the iPhone, even if they were sent from my computer, before I even got the iPhone?

Thanks for any tips or descriptions of how these two transitions (Gmail to IMAP, then the iPhone) work!