VIC-very important client. It's granted by your SA or store manager, you will get special invites, good spot on WL, and those lovely VIC gifts like paper weight, key chain, cards, etc. It really depends on your relationship w/SA, some people spend quite a few in store, but never granted VIC, yet some people hardly frequent the store are granted such status.
euroaddict, to be honest, i'm not sure if the record is shared international among boutiques. but i do know boutique, eluxury, Saks/NM/Macy don't share same data base.