1. His tomb was found and excavated at Herodion in 200# by Netzer; the evidences indicate that it was desecrated not long after his internment, indictating how much he was disliked. Josephus tells the story of how Herod, knowing that he would not be mourned, had 70 Jewish elders arrested with orders that they should be killed as soon as he died so that there would be mourning at his death. Thankfully, his daughter ordered that they be released when she discovered the order. Most modern scholars discredit the story as having any historical basis, but the fact that Josephus would report, even if only fictitiously, such an incident is proof of the low a view he and his contemporary held of Herod.
2. Priests were required by Num 8:24-26 to retire by the age of 50; so Zechariah could not have been older than 50.
3. V26 asserts that the angel Gabriel visited Mary with the pronouncement of her conception of Jesus in the "sixth month." The pronouncement of John's conception here would, therefore, have occurred 15 months before the birth of Jesus. If we reserve 2-2½ years (Matt 2:16) for the time between the birth of Jesus and the death of Herod, then this story would be set about 4 years before Herod's death.