You forgot about the weak vampires. They don't start out being able to capture souls and turning people. They feed on some of spark of life.
They gain power the more souls, and or spark of life parts they take. They can even grow with talents awarded by the soul they have stolen.
They are ageless, Which means the age you become one, you will stay till you die and when you die the first death is permanent
can only go out in night.
2,) Undefined mechanic, however they said you have to do it in order to sustain the soul the vampire is missing. Read, a ticking time bomb.
3.) Obviously, and in some respects an NPC life could very well be more "beneficial" to a settlement than a PC's slightly lower soul loss from being CDG.
4.) The lich phylactery isn't something you can eat, I would expect because vampires aren't soul reaver vampires. Unless mechanics are working otherwise..
5.) You will have to be a strong vampire to be able to turn other's into the tribe.
6.) We don't know the mechanics. I assume it'd be your action instead of CDG when you CDG you have a different thing that happens.
8.) See above, but we don't know what talents he gains or the stat increases that are achieved while being a vampire.
9.) We don't know, but I assume you would understand what had happened when you have to buy another spark of life, or with an event log on the time of log in.
10.) be a hrothi, if you wanna vamp, their settlements aren't in the sun :D