You can't access to email without a Blackberry
data plan. Period. Lots of folks are using BBs without the added expense of a dedicated Blackberry data plan but they give up most of what makes the BB so special.
You can hide the Enterprise Activation Icon but you can't remove it. It's part of the OS and coded into it.
With Desktop Manager you can sync contacts and calendar events to a computer, but not email. Blackberrys don't sync email. With BES everything will match (opened items on the BB will show as opened in Outlook, deleted items in Outlook will be deleted on the BB, etc.) but Blackberrys don't sync email. As for the version of Desktop Manager and handheld OS version, they don't have to match. The latest stable DM software is 4.2. SP2. The folks using DM 4.3 have reported all kinds of issues and it looks like for now the best release is the older 4.2, available for free download: BlackBerry - BlackBerry Desktop Software | Applications to Synchronize Your BlackBerry and Desktop Data