Would be funny if it were some character we've never seen before. Not that these writers would ever do that, but still.
Maybe. But dramatically it would have more impact if was someone they knew on E1 like Wally or Eddie.
We can rule out the E2 people we have seen so far - Joe (kinda dead now anyway), Barry, Cisco, even Iris.
We haven't seen yet an E2 Wally or Eddie.
E1 Wally has been going on about speed and being fast. My weird theory is Zoom is the E2 Wally. He either was affected by the explosion and gained speed and wants more, or he somehow found out about Velocity 6 and stole it and used it and has become a speed junkie so it won't wear off.