Electron velocity

HarryDaniels

Two questions
Both of these occur in a vacuum:
If a photon has the exact energy to electron-positron pair product, since the electron and the positron are the same mass, if stationary would have an energy of Mc^2. Since they are moving would there energy be (of one fermion):

E=(mc^2)+(1/2mv^2)
or
E=mc

If that is true does that mean the energy of the photon (in a vacuum) would be:

Ey=2((mc^2)+(1/2mv^2)
or
Ey=2(mc^2)

Then, in a vacuum, would the electron and the positron collide? The second question is the previous one and what is velocity needed for anihilation?