If you'd like to hide the calculated columns from the DispForm page (when you're viewing an item)...
In your list, go to the Settings page.
Click on Advanced Settings
Change the setting "Allow management of content types" to YES
Click OK.
Now there will be a new section in your settings page, called "Content Types", and there will be one content type listed in there. For example, if it's an announcements list, the content type will be Announcement. If it's a custom list, the content type will be called Item.
Click on the name of that one content type
Now you see your columns listed. Click on the name of the column to hide, and change it to "Hidden".
As far as the alerts go, this is a bit more complicated.
Read my friend, Brett Lonsdale's paper on modifying the alert notifications:
http://www.combined-knowledge.com/Downloads/Modify_Alert_Notifications.pdf
Specifically, read the part about the Properties element.
Laura Rogers