What is the difference between dedicated server hosting and shared server co-location?

Your server co-location pricing is based on "u's", what is a "u"?

What if my server has a problem while it's Co-located at your facility?

Are your facilities carrier neutral?

Can I get T1's, phone lines, or other connections to my equipment?

Do you allow hosting of Spam type email services?

Can I administer my server remotely?