17. When clicking on the To: field in an email, my addressbook appears to be empty

Follow the descibtion from the Microsoft site:
http://support.microsoft.com/default.aspx?scid=kb;en-us;287563&Product=ol2002

18. My Addressbook is sorted alphabetically by first name. Is there any way to change this to sort by last name?

You can change this.
go to Tools > E-mail Accounts > View or change directories or address books > Change.
Tick the 'file as' box.

19. How can I change a field (e.g. a company name) in several Contacts at once?

http://www.slipstick.com/outlook/searchreplacecompany.htm

20. How can I remove an Addressbook entry that points to a folder that has been moved?

Click on the menu Tools > E-mail accounts > View or change existing directories or address books > Outlook Address Book > Change

21. When creating or forwarding an email message using Outlook 2000, scrolling through my addressbook causes the program to close unexpectedly.

If it always occurs at the same point as you scroll down the address book, examine all the Contacts in that region to look for a corrupt or unresolved address. If you find none, remove the Outlook Address Book Service, close Outlook, run the Inbox Repair Tool (scanpst.exe) on your .PST file, then re-add the Outlook Address Book Service to your profile.

22. When I open the list of Contacts in the Addressbook, there are two entries for each name - one is the email address and one is the Fax #. How do I combine them in a single entry?

http://www.slipstick.com/contacts/nofax.htm

23.) My Addressbook cannot be opened, it is grayed out.

Try removing the Outlook Address Book (Tools > Email Accounts), restarting Outlook and adding it back in.