How do I control how often iCal pulls new data from FileMaker Server?
Open preferences in iCal and click on the Accounts tab. Find the account for your FileMaker calendar and the Account Information sub tab has a field saying "Refresh Calendars:" You can elect to do this as frequently as every minute, but remember that these are queries to your FileMaker server, so only do it as often as you need to.
You can also refresh a calendar by right clicking (control-clicking) on the calendar's name in iCal and selecting "Refresh".
On the iPhone
There is no similar manual way to force the calendars on the iPhone to refresh. This can be very frustrating when you're testing Zulu, but in everyday work it isn't that bad: the iPhone seems to refresh every 10 to 15 minutes.