1. The Metus is a Bow, not an xBow. You can probably go STRless with enough funding, but ~30 STR isn't going to affect you all that much.
2. I would say Arrow Blow now, since it semi-mobs (hits 2 targets). Pretty sure you can max both, but either way; both are pretty much unused by 2nd job where Arrow Bomb/Iron Arrow become your main skills.
3. If you mean 3rd job skills, pretty much everything gets replaced except Strafe if you're an xBowman... But they get Ultimate Strafe, which goes over it.
4. I would say Dragon Breath. It's not very useful, especially without minimum range. Maybe put a point into it, but no more than that. You probably won't ever use it.