iCal: Persisent error and sync issues

I repeatedly get an error message on my ical about a meeting that couldn't send:

I have tried to reset (per instructions from folks here) and it does not go away.

How would I delete and reinstall ical while keeping my current meetings?

Finally, ical on my mac does not sync with my iPhone ical does not sync with ical on the mac.

I can't believe these are even issues but any help to solve them would be greatly appreciated.