Vampires require regularly feeding on blood in order to survive. If they become starved of blood, they will go into a feeding frenzy and attack anything nearby that might give them blood. Vampires are vulnerable to sunlight and fire.
All vampires have enhanced physical strength and speed, and can see perfectly in total darkness. Their age is frozen at the time of transformation. Mages who become vampires will need to expend blood rather than mana to power their abilities, but as such, will still be able to use their abilities even if little to no mana is available.
In order to transform a person into a vampire, their blood is drained and then they are fed vampire blood. This can still be done even in the absence of an actual vampire, if the appropriate blood has been procured and preserved. In the absence of any vampire at all, a person can still be transformed by use of a Blood Magic ritual.