Enterprise Activation is only used if you're in a corporate environment with a Blackberry Enterprise Server, which is sounds like you're not. You can hide this (or any other of the icons from the home screen) by selecting an icon, holding down the
key and then pushing in the scroll wheel. This will pop up a menu that will allow you to move and/or hide icons, so simply select "Hide Icon" and it should be hidden.
If you're not using a BES or a Microsoft Exchange server for your e-mail, you need to either have your mail forwarded
to your Blackberry (using your @<carrier>.blackberry.net address), or you need to set up your Blackberry Web Client to retrieve mail from your other mail accounts. To do this you have to log on to a web page provided by your carrier (which you normally get from your carrier, but the link might be around here somewhere if you search the forums).
If you forward your mail to your blackberry.net address (which would have to be set up from
your e-mail provider) then the delivery will be instantaneous. Setting up your BWC/BIS to retrieve your mail will result in a delay of up to 15 minutes before your mail shows up on your device, since it only checks every 15 minutes.
I'd recommend checking out Mark Rehjon's excellent FAQ
here on the forums for more information on this and whole bunch of other frequently asked questions.