1- Reverting to an older version is not a solution. If something is corrupted you need to work it out….
Have you tried to save / backup settings, then remove/delete all weaver Themes and plugins completely, then reinstall them from scratch?
2- If you mean Wordpess Custom Menus in Appearance > Menus, this is independent from the theme. WordPress has some bug/limitations if you have a very large amount of menus, there was a post on a solution here but I don’t remember where it is
3- see 2