For all your class building needs...
http://archeagedatabase.net/us/calc/
Classes are put together allot better than Rift, haven't really found any back-braking OP builds. But don't think you can switch back and forth ya can't, you have to earn a lvl's worth of exp to learn that skill. So if you want a lvl 5 required ability, than you have to earn 5 lvl's with that skillset in your build for you to learn that ability.