Your name, age-- [a pause, before he reminds himself of circumstances and moves to elaborate.] Age when you died, and how long you've been undead.

And if healing potions still work for you.

For safety reasons, I wont attempt any medical-related experimentation with your blood outside of the one I'm planning. [which negates quite a lot of the standard questions nehan has, and the undead part just... removed a good number of them as well.]