One snag, on Macs capslock works differently. It doesn't invert when you press shift. Shift + A with capslock on will still result in an uppercase A.
They also have authenticators before a lot of other people had them. And please use one if you do. Battle.net accounts are targets.
You don't have to do that, my password has capitals, but after I found out the shift the alphas to only one case I stopped typing the caps.
IIRC, the client encrypts the password using some variant of SRP6 plus some additional magic, but the last time I dabbled in wow emulation was quite some time ago.
EDIT Here's a link to a moderator confirmation: http://eu.battle.net/wow/en/forum/topic/2679778775#3