I've noted these, though one point here is that events could never recur indefinitely because the system adds all the future events in to the calendar immediately when you create the recurrence. And adding an infinite number of events would take too long :-)

The last <weekday> of month feature has been mentioned before and I agree that this would be the most useful addition of the ones you mention. The others can be worked around (with a bit of faff perhaps) but finding all future months with five Mondays is a task better left to computers I think!

Cheers

Joe