I'm not so sure about the absence of a V in Greek. Modern Greek definitely has it. Beta is pronounced as a V as in velocity (the letter's name is actually closer to "veeta" in modern) and not as a hard b as in ball. In Modern the hard B is indicated by a combination of mu and pi and is largely restricted to loan words that recently came into Greek from English (Bar = mu pi alpha rho, Balcony = mu pi alpha kappa and so on).
Pronunciations have changed so maybe the letter was pronounced differently in ancient Greek, but my thought is no. We know for certain that in Koine (think of it as Middle Greek) which is the version the Gospels were written in, that beta was pronounced as a V.
A W sound did exist in ancient Greek and was indicated by a letter called digamma that has since vanished from the alphabet, along with the sound.
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