Okay, so I plan on doing a vampire-based, stealth-specialized custom class. I tried to find a site in which there's lists of custom classes, but I can't find any.

In your opinion, which skills should I put as major ones? Which birthsign is appropriate?

Oh, and yes. I'm using the Dark Elf. I mean, their Resist Fire racial trait outright cancels the weakness to fire vampires naturally have, so it's definitely a bonus that you should have.