1. Does not look like it.
2. It appears this way.
4. A lot
5. No, but it does seem that way, wish they had wider platform support and made the info easier to access.
Good luck. I'm in the same boat I'm afraid.
There is no website to manage your clan. The only way to manage it is through the limited in-game options and through the mobile app. If the mobile app doesn't work for you then you are out of luck on managing a clan. Very poor implementation by Beachhead yet again.
The website you used for early registration does not exist anymore as it was just for a one time import and not meant to be your clans page.
Elite had a LOT of issues and there are plenty of reasons to move away from it. It wasn't convenient to move away from it, but it did have a lot of good reasons too at the same time.