If I cure the Vamp lord to use the Face changer, and go to Serana to get it back, will I have to regain all the VL abilities? Or will they still be there? Also, how often can you regain Vamp Lord? Is it only once like with Aela? Thanks in advance to anyone who can answer.

You keep all perks!

You keep all the perks you unlocked, and I believe as long as Serana is a vampire you can still become one.

Sweet, I'm off to get a haircut then! Thanks guys.