You should actually put the copyright year as of when the site was first created, future copyright is then inferred for all years after that without actually having to write them is my understanding.
the use of a date range is to signify that not all the works were created at the same time, so each revision may change the year, so no it should not say 2005 it should say 2000-2004, if it simply stated 2000, it would imply that the whole thing was created in 2000. However since 1989 it has been unesecary to include a copyright notice at all since copyright is implied anyway, there is no requirement for a copyright notice.
Huw's correct. There is no need for a copyright notice. It looks professional, though, and is a reminder to others that you're going to protect your intellectual property.