We should gather what we know about the vampires so we can better know the best way to handle them and/or take advantage of their strengths. I will list what I've been reading as common for vampires and hope others will add their discoveries:
A} Vampires usually(always?) attack sleeping victims
B} Vampires usually kill their victims by draining all their blood, except for large sized dwarves if the vampire has been well fed.
^ {1st reported by trees referencing Toady quote)
C} There's no reported cases of vampires having trouble walking around outside {lore conflict}
D} There's no reported cases of victims rising from the dead and becoming vampires themselves or even lesser vampires(thralls).
E} Vampires can be identified from engravings/decorations. {1st reported by Wastedlabor)
Vampires can also be identified if a dwarf has a deity, you can check the deity on its relationship screen, then (v)iew it. This lists the various curses it has given out, and if the deity has cursed the dwarf to be a vampire, you'll find it listed there. Beware some vampires might have been born into the world and thus not cursed. {1st reported by Stormfeather)
If anyone accuses one of the original 7 of being a vampire on the justice screen the accuser is usually a vampire trying to shift the blame according to a posts by ThreeToe on the main page. {1st reported by Astrobia referencing Toady quote)
Some vampires will own or wear lots of jewelry or seek positions of power in the fort or have lots of high skills, yet this is not always true.
F} There's no known method for restoring a vampire back to being a normal dwarf. {golden salve?}
G} There's no known method for protecting your fort from vampires entering {crosses, holy land, etc.}
H} Deconstructing the bed of a targeted vampire victim appears to stop the attack. {1st reported by Wastedlabor}
I} Reported benefits for a vampire unit include: don't need to eat, sleep, or breathe; they can't feel pain, pass out from exertion, feel nausea, get dizzy, stunned, paralyzed or have a fever. The unit has double their strength, agility and toughness along with making all attacks on them have half as much force. {1st reported by trees)
J} Nicknames in the status screen work as normal for vampires, but the nicknames don't show up in the (u) dwarves list, they just show up as their real name there. This sounds like a bug which is why it's not listed with the other identification methods. {1st reported by Quietust assisted by Stormfeather)
K} Workaround to decrease the number of vampires in the world is when you generate a world, go to advanced options and set the number of vampire curse types to 0. This won't stop any vampires which were created in the world, but will stop any future dwarves from being cursed as vampires. {1st reported by PTTG?? then assisted by knutor)
Art of War: Turning an obstacle into an advantage
Stationing vampires doesn't keep them from going to feed in the dormitories on sleeping dwarves. {1st reported by crossmr)
Burrowing works for keeping them outside as always training. {1st reported by Wastedlabor)
Placing a vampire into a small room and spiking him for blood splatter then filling the room with water to use as a well for drinking will turn everyone into vampires. {1st reported by i2amroy)
If vampires don't need to sleep or eat they would be great walled inside a tower outside with windows and a roof allowing a permanent alarm for your fortress. {1st reported by NTJedi)