We're in the process of setting up a high availability system in two
separate geographic locations using SQL Server 2000. One will be used
as primary production site, the other replicated to be used in two
ways: 1) hot backup site in the event 1st site is unavailable, and 2)
for purposes of acting as primary when original primary is being used
for data extraction and table updates. If I'm not mistaken, this would
require merge replication.

How would we get the replicated sites synchronized if we need to make
any changes to database structure, upgrades, bug fixes, etc?