So, couldn’t Tesla revamp from her blood?
Exactly how these things work isn’t really clear. Why didn’t the Source Blood turn Magnus into a vampire, for instance?
It’s Emperor Palpatine!
When the fake priest took off his glasses, he looked familiar. Of course, at this point, I’ve probably seen just about every actor who worked in Vancouver in the past decade on at least 2 different shows, but still. 
Just a WAG, but maybe he was already descended from a vampire and the source blood activated those recessive genes?
I don’t recognize the actor, but yeah, he’s probably been on Stargate, Smallville, and BSG at some point. 
That’s essentially their theory. That’s why everyone got different powers.