You are correct: DX helps with bows, while PE is for guns. The faster you are, the more attacks you'll get. (Unless you're building a skill that requires it, like Firearms or Spot Traps, as far as I'm concerned PE is a dump stat.) Also, take apprenticeship and expertise ASAP, and mastery as soon as it's viable.

I'm honestly unsure whether Prowling helps with bow accuracy or damage; I've never bothered with it, as it always seemed to be purely a "sneak past the guard" tactic. What I do know is that you can target body parts using a bow, the same as you can with a gun: it lowers your overall chances to hit, but increases the chance of a critical hit if you do connect.

Magic advice? Hasten, from the Temporal college, doubles your attacks in turn-based mode; Tempus Fugit speeds up your whole party, while also slowing your enemies. Minor Healing is essential, and Shield of Protection is pretty handy (though IIRC its spell effect interferes with Prowling).

Either boost your CN to increase your Fatigue recovery rate, or stock up on plenty of Fatigue slowers and restorers. You'll also need WP to be able to learn the better spells. (Teleport is extremely handy, from the mid-game on.) In any case, the more MA you have, the better any magic weapons and items will work for you; your MA has to match or exceed the item's MA to get the full bonus.

I agree with you about the manual, btw; not only is it informative, it's a blast to read. Though from one "old gamer" to another, an in-game tutorial would also have been nice. (Though I suppose, in a sense, that's what the Crash Site was all about.)

Also, a minor spoiler protip: I won't tell you what (or where) the best magic bow in the game is, but I will tell you that it is NOT the Arcane bow. Have fun, and good luck.