The toons should be very similar to WoW. For example, there's a Witch Elf that should be very much like a rogue. She uses poisons, is very quick and agile, puts out a lot of damage very quickly but lacking in armor. There's also the Bright Wizard which should be very much like a mage putting out heavy spell damage. Check out this link, it will show you a little more about the armies.
http://www.warhammeronline.com/engli...o/armiesofWAR/
The closest thing to a Lock that I saw was the Chaos Zealot but then again I haven't read about all of them.
http://www.warhammeronline.com/engli...ers/Zealot.php