4.3 Upgrade errors and problems

SO many problems with this update:

1. Main top menu was changed to a sidebar menu. We could not change it using the new customise feature on the page and the Widget area on the Dashboard is completely frozen.
I deleted the Sidebar menu and the next on on the list alphabetically was automatically used as the Main Top Menu. A workaround was used where the Main Menu I wanted was just renamed so that it was the first on the list alphabetically and was automatically used as the new top menu.
2. The Visual/Text editor options are non-responsive when editing a page.
3. The ‘Add Media’ button is completely unresponsive.
4. All the suggestions on the forums recommend deactivating plugins one by one etc etc but this does not work.

Is there a fix for these issues?