Hello - did you figure out a way to fix your question above?
3. Deleting events manually: I'm willing to take the brute force approach but there is a further complication: When I try to delete events that are attached to other people (who invited me or vice versa) iCal will prompt me to say it will decline the invitation. There used to be a way to simply not send a notification but now you are required to when you delete an invite. There is another handy tool by the same fellow called "iCal Reply Checker" which prevents Mail from spamming people, however it doesn't seem to be able to stop iCal from talking to iCloud which will send the decline notice on your behalf.
I'm having the same problem and am trying to figure out how to fix it!
Thanks for any help you can give....