Katrina, Rita, Wilma

I used to wonder if and why hurricanes were given female names.
I found out, there are male names for hurricanes as well.

Then I wondered about how they assign names to hurricanes. Is it the first person who sees it?
Is it the town it first hits?
Apparently, there is a pre-approved list of names for hurricanes.
2005 Hurricane Names
So, we're on the last name now, Wilma. Yes, it goes alphabetically.
What happens if there is more hurricanes after Wilma? Is there a backup list? Do we start 2006 list?
Who assigns these names and keep them non-duplicated over the years?