Run an applescript whenever a certain person signs onto the Messages buddy list

In more than one case now, it looks like multiple copies of the name will show up. You have to either check the buddy picture or other features (for example, video chat doesn't show up for Facebook) to determine which network you are contacting them on.

To set single alerts on all birthdays, you can avoid a script altogether:

1. Open Calendar Preferences in Calendar.
2. Under General, tick "Show Birthdays calendar".
3. Under Alerts, set an alert for "Birthdays".

I haven't taken the time to actually write up an AppleScript for the double alarm parts, but this article seems to cover scripting calendar alarms quite nicely. I would imagine you would just need to create a file or list in the script that contains the names of the events (which you can deduce from the standard naming convention Calendar app uses).

Also I am using Mountain Lion with Calendar app. I can't recall if the steps above work on older versions of iCal.