ICloud – Does Apple scan iCloud e-mail like Google does with Gmail

Despite some positive reports in September, it looks like you won't be able to merge Apple IDs. You can, however, set up iPhone, iPod Touch, iPad, Mac or PC to use two different accounts for iCloud and purchases:

iPhone, iPad, or iPod touch:

When you first set up your iOS 5 device, enter the Apple ID you want to use with iCloud. If you skipped the setup assistant, sign in to Settings > iCloud and enter the Apple ID you’d like to use with iCloud. In Settings > Store, sign in with the Apple ID you want to use for store purchases (including iTunes in the Cloud and iTunes Match). You may need to sign out first to change the Apple ID.

Mac:

Enter the Apple ID you want to use for iCloud in Apple () menu > System Preferences > iCloud. Enter the Apple ID you want to use for store purchases (including iTunes in the Cloud and iTunes Match) in iTunes > iTunes Store.

PC:

Enter the Apple ID you want to use for iCloud in Control Panel > Network > Internet > iCloud. Enter the Apple ID you want to use for store purchases (including iTunes in the Cloud and iTunes Match) in iTunes > iTunes Store.

Note: You can switch the Apple ID you use for store purchases at any time. However, you can only change the account you use for any iTunes in the Cloud features once every 90 days. See this article for more information.

You can configure Gmail as IMAP account type. That will sync your mail messages between multiple mail clients.

That leaves open your request to not retrieve all 3Gb of mail when first configuring the program. There I haven't got an answer only a possible workaround. Many mail clients limit their download sizes when they are on low bandwidth connections. You could try to limit your bandwidth, for exmample to 8 kbps, with these terminal commands when having Gmail configured to use secure imap:

$ sudo ipfw pipe 1 config bw 8kbit/s #create reduced bandwidth pipe
$ sudo ipfw add pipe 1 src-port imaps #sent traffic from imaps thru pipe

As Gmail is not offering an Exchange server, only ActiveSync compatible, you will never get an exact similar experience with Gmail.