Marvel Chronology Project

I have a few questions regarding the Asgardians and their Ragnarok cycles.
1/ There was one about 2000 years ago (the light of the destruction of Asgard was purported to be the Star of Bethlehem) and there was another one in the modern era. Do we have any references as to when any earlier ones occurred? Or to how many has occurred?
2/ Have the Hyborian era gods such as Borri and Ymir ever been confirmed as being the same as the modern ones?
3/ Have their been any definitively established dates for the Asgardians prior to 2000 years ago. For example, Thor: The Truth of History depicts Thor 4000 years ago. Was this the modern Thor or an earlier incarnation?

Forget the Eye's story - a Ragnarok cycle, per all the stories in the past few years, essentially reboots reality, so "time" is irrelevant.

This only didn't happen last time because Thor aborted the cycle before reality (in the form of the Norns' tapestry) was unwoven.