I'm new to this game and I find myself somewhat confused about the way the class system works in the sense I guess of maximizing the potential of my character.

I've rolled a monk and was feeling quite proud of myself until I stumbled across the whole cross class skill concept and suddenly I felt a bit overwhelmed. I'm not really sure what to do. Should I level my monk to max level then focus on subclasses? I have lancer to 15, should I level him to 50 as well to get all the cross class skills possible? I think the Monk can also use Marauder skills too, should I level that as well? Another question, is it possible to have every class maxed on one character?

This entire concept is pretty new to me, so forgive the noobishness of this post.

Thanks