As for the second date:
The fixation on the First Jewish-Roman War (66-73 C.E.) by the Jehovah's Witnesses and other Christians is so very odd to me.
The Second Temple did fall in 70 C.E., but it was by no means the end of the Jewish people. And it is not fully believed by academia that the Christians fled to Pella.
It was with the Bar Kokhba revolt (132-135/36 C.E.) when the Jews were finally barred from Jerusalem. The revolt was crushed and all Jews were removed and barred from Jerusalem by the Romans in 135 C.E.
The original Hebrew Christians had a church in Jerusalem up until then. In fact, the last Jewish bishop of Jerusalem was Judah Kyriakos, said to be the great grandson of the apostle Jude, a cousin or other close relative of Jesus of Nazareth.
Because the Romans had caught on to the Jewish idea that the Messiah would come from the House of David, they began to slaughter as many of them as they could after 70 C.E. Since the first bishop of the Jerusalem church was St. James the Greater, a relative of Jesus, his replacements were all relatives and descendents of David, or so they claimed.
Due to the Roman slaughter of the Ben David line, the Jerusalem church had 16 bishops from 33 to 135 C.E. when Judah Kyriakos and his Jerusalem congregation dispersed after Bar Kokhba was crushed.
So the date for the Roman diaspora of the Jews begins not in 70 but with 135 C.E. That is when Jerusalem was emptied of all Jews and the Christians. And the "run away" to Pella may be an embellishment of sorts. There is too much evidence against it.