Mirroring… also licensing!

I have never tried to mirror a hard drive. Is it possible to do in W2K server? or do I need a raid solution.
#2. I wish to install w2k server on a single domain model but across 5 separate locations within Canada. The links are an acceptable range.
I intend to install w2k server on 5 separate servers w/ global cataloges DNS , DHCP on each for failover reasons. I will have a total of 50 users accessing our domain. Do I buy a separate W2K server softwrae for each server? and should I split up my user base for each or should I purchase 50 cals for 1 server?????

Thanks
Merv