Personally, I don't bother with bows on Dregs...BS 2 makes it nearly impossible to hit most of the time, since you'll often be over half range, shooting into cover, or moving. It's not useless, but I prefer to save the gold. If you already have them, I'd say keep them unless you need the money from selling.
To start, I've gone one of two ways with dregs. I've either armed them very cheap with maces, or go with double hand weapons. With one attack and WS 2, they won't hit a lot, but they will hit hard. They're also good at taking out knocked down models, which has the nice bonus of more xp.
For skills, Strongman is priority for dhw; I prefer Mighty Blow or Resilient otherwise. If you don't get crappy advances, dregs can become pretty formidable quickly. But then you'll inevitably get one with LD 9 and I 6, but still WS 2. Such is Mordheim.
I like Strength/Speed on ghouls, but Combat/Strength works too. I like to have a model outside of the vampire who can quickly redeploy or go for objectives, which is why I pick speed. Keep in mind you can pick up Combat later with a lucky exploration roll. You can't count on it, but if you do roll it, you can have combat, strength, and speed.
Resilient is always always always my first choice for a ghoul hero, because it means they can't be crit by strength 3 in melee.