Hi there! Yes, strength is the ability which increases damage, melee and ranged. Dex affects melee accuracy, evasion and some resistances. Perhaps it helps if you think it like this: more strength allows you to hurl the projectile weapons faster thus causing more damage. Now, I agree this does not make that much sense for bows but we wanted to keep the system simple and consistent so strength boosts all physical damage.
The primary effect of weapon skills is to increase Attack Power with that weapon group and unlock some weapon group specific talents (and also increase accuracy for melee weapons). Weapons skills have some stat upgrades for flavor. Those upgrades may not necessarily make the attack with that weapon any better. So for example, Missile Weapons not only increases Attack Power with bows (and grants special things with bows at level skill levels) but as a bonus it also increases character's dex and therefore helps with evasion and therefore makes the rogue a better frontline character. We hope that these flavor bonuses make the level system a bit less one dimensional and therefore more interesting.
Hope this helped!
