The dev stated quite clearly in the E3 demonstration of Dawngaurd that the Vampire Lord is primarily a spellcaster battle form.

So unless you find a way to deepen your magicka reserves while transformed you'll be relying mostly on fang and claw. In wich case a werewolf would probably be a better fit for you.
Yep. Matt Carafano did say that the Vampire Lord Form is a heavy spellcaster. Therefore, the deeper your Magicka reserves, the better, especially considering your equipment enchants don't carry over to Vampire Lord Form.
Should be able to, I don't see why not. Like.. a werewolf, it's the same effectiveness, no matter what archetype.
Not quite. A low health Mage that goes into Werewolf Form is going to get wrecked in seconds, while a high health Warrior that goes into Werewolf Form will last a little longer. The lack of Armor Rating is still a huge problem for Werewolves though. Which is something that i've noticed that Vampire Lords don't seem to have a problem with. In the footage of the new Vampire Lords and the buffed Werewolves, i see that Vampire Lords don't seem to take much damage when hit (One even melees a damn dragon), but the Werewolf still loses big chunks of health with every hit taken.