User blog comment:JAlbor/Dawnguard: What Everyone Should Know/@comment-4324788-20120630234138/@comment-2086180-20120704045043

Probably a bit late for an answer, but nevertheless...

The crossbows work great in conjunction with certain perks, such as ranger so you can move quickly with a loaded bolt or quick shot to bring the reload speed up to par with bows. Power shot is a must though, the 50% stagger chance combined with the crossbow's built-in stagger effect with 50% (I think) chance to stagger means that you will always stagger all but the largest enemies.

As for exploding bolts, they... well, explode, with whatever element they are. Shock would definitely be the most effective to use in general but for enemies with specific weaknesses (e.g undead tend to be weak to fire) use their weakness.

The Dawnguard don't care about werewolves, as long as you're not a vampire you're fine. Also, you can still upgrade werewolf abilities with perks.