Heya bro,
Good questions, was asking the same kind of stuff when I started out...
From my experience, the stats seem to have varying levels of effect - even though they affect the same stat. For example, raising agility 10pts might give you 3 evade, while raising quick 10 would give you 7 evasion. Evasion seems to be the primary reason to jack quick - its the main modifier.
To answer your other question, I don't think its necessary to start a new skill unless you want to have 2 specialties, ie. xbow & bow.
cheers,
Cal
