Mail, Contacts, Notes not responding? Have forced quit all and rebooted to no avail.

It looks like iCloud corrupted a bunch of preference files. Recovery will be tedious.

Back up all data.

Hold down the option key and select

Go ▹ Library

from the Finder menu bar. From the Library folder, move the entire contents of the subfolder "Caches" (not the folder itself) to the Trash, then log out and log back in. Empty the Trash. Test.

If the problem is not solved, open the Library folder again in the same way and move the entire contents of the subfolder "Preferences" (not the folder itself) to a new folder on the Desktop (not to the Trash.) Log out and log back in. The account will then be pretty much in a clean state. Test. If you can still reproduce the problem, then put the Preferences folder contents back, replacing any that were created in their place, log out, and log in again.

If you can't reproduce the problem in the clean state, then start putting things back in the Preferences folder piecemeal, starting with items that seem unrelated to the issue. I can’t be more specific. After each group of items, repeat the log out/log in cycle and test. At some point, the problem may reappear, in which case you know that something in the last batch of files you restored is at fault. If it never reappears, the problem is solved.

Delete the preference files of the apps that were hanging and recreate their settings. The file names should make it pretty obvious which ones they are. Everything else you can put back.

I can't vouch for what will happen if you re-enable Documents & Data synchronization. You seem to have triggered a bug in iCloud.