Contact sync seems corrupted. How to recover? iCloud, laptop, iphone work fine. iPad shows some entries in duplicate or near duplicate, and when you delete one, both get deleted. iMac no longer syncs at all though set to sync.

Question

iPad seems buggy, iMac simply not connected to syncing contacts (and focusing on it, not on Safari bookmarks either)
iPad example:
Two entries exist for a contact on iPad, identical or differing slightly (e.g. a space being added before a word or identical in one but not the other). I delete one of the entries and both entries disappear from ipad, iphone, icloud. Entry persists on iMac. 
iMac:
iCal syncs. Mail syncs. Calendar doesn't. Bookmarks aren't syncing either: A recent add to Safari bookmarks that has synced elsewhere has not synced on iMac.
On the iMac, when I go to iCloud in network settings all boxes are checked except Photo Stream, Back to My Mac, and Find My Mac. Account details show my email address, my name and Description "iCloud". The amount of GB available in iCloud storage, which matches what I see on my iPhone.
iMac: OSX 10.8.5, 2 GHz Intel Core 2 Duo

Answer 1

Thanks for the suggestion, Barney-15E. FYI I am not running both iCal and Calendar. Just Calendar. Me bad for using the old name and new name interchangeably.
Tackling the iMac problem: In iCloud network preferences, I unchecked Safari then soon after rechecked it, and your suggestion appears to have worked: a bookmark recently added on one of the other devices appeared in the iMac Safari bookmarks. So far so good.
Did the same thing with contacts. The iMac took a couple of hours to restore the sync setting, but it finally completed the task. The computer was laboring so I rebooted. Then I opened the contacts application and saw the spinning grey bars next to the "iCloud" heading above my list of contact groups. Some time later the spinning lines were replaced by an exclamation point. I clicked on it and got the message that the operation could not be completed because of a "CoreDAVErrorDomain error 1..". Subsequently, after much spinning of the line wheel, I have gotten either the exclamation point with the CoreDAV message or a lightning bolt icon. Whether exclamation point or lightning bolt, clicking on it provokes a long period of the spinning line wheel. And looking at some telltale contact discrepancies between the iMac and the other machines, nothing seems to have changed in terms of merging the discrepancies.
Searching for the error message in the support community, I see this has happened to others, and they have had some success in following a list of steps starting with archiving the contacts, which I have done. Don't think I fully follow the other steps, nor am I sure they apply to my situation.