Q: can i sign up as a new user to iCloud and get an @icloud address and/or get a second icloud address as an existing user

Each iCloud account only has a single email account.  You can create a second @icloud.com emal alias that will receive email in your existing iCloud inbox, as explained here: http://help.apple.com/icloud/#mm6b1a490a.  If you then wanted to separate the email, you could set up a rule on icloud.com that would move your @icloud.com email to a separate folder (see http://help.apple.com/icloud/#mm6b1a3f8a).

You could also set up a second ("secondary") iCloud account on your device by going to Settings>Mail,Contacts,Calendars>Add Account>iCloud and entering a different Apple ID.  This would give you a second iCloud email account.  However, there are limitations with secondary iCloud accounts to be aware of.   Only the primary account can be used for Photo Stream, Bookmarks, Documents, iCloud Backup and Find My Device.  Also, push email only works for the primary account; secondary account email is fetch.

You can also create aliases at icloud.com under mail settings.

allows you to create temporary email addresses that just go to your default email address.