What a smashing chap Doctor Gott is.
Indeed.
1) Doesn't answer the question why existence and not non existence.
Neither does anything you've said.
2) Doesn't challenge any cosmological argument where time is immaterial. E.g contingency and necessity.
They're obviously bollocks for other reasons that have been explained to you. It does show (again), however, that the universe is not obviously contingent on anything else. And a 'necessary entity' is
still gibberish.
3)There seemed to be different types of universes branching of suggesting the endless loop is not actually closed.
It's closed at the start. If you track into the past along time-like curves, you end up in a loop.
4) Why does it start with a looped universe?In other words is it a construct in order to eliminate a universe with a beginning?
It's a possibility. I really just posted it to point out there there are possibilities that mean the universe could be said to have created itself.
In fact, the mere concept of the space-time manifold removes any beginning for the whole thing. As Gott points out near the end, we are just talking about four-dimensional 'sculptures'.