I'm not really sure how the vocations level up, but it seems like you get experience for using your skills and abilities. I don't believe you actually get anything towards your vocation from quest rewards, or by simply standing around while the pawns kill everything (could be wrong about that), although you do get discipline points.
Here's a pretty good source of info:
http://dragonsdogma.wikia.com/wiki/Dragon's_Dogma_Wiki
You can easily see what stats your character would get per level up while being a specific vocation.
Also, having an extra dagger/bow user in the group isn't a bad approach at all. At least not if your character is one, although I doubt I'd bother with having two archer type pawns out of the three you can bring. Would take down most enemies fairly easy, but just like going fighter/fighter; enemies requiring some kind of magic attack to beat would be annoying.