It's not as common as using it with guys, but yes you can use it with girls. Girls also use it with other girls.

Its meaning : "A kind of dandy; especially, one characterized by an ultrafashionable style of dress and other affectations". So of course you can say dude to a girl very close to you. Its informal word.

dudette =)

Hi... If you really want to use it perhaps you can with young girl but don't use it with a woman... It won't be appreciated...