CPD

I have a standard WRX registered in May 2006 with 4900 miles on the clock. The only service items changed appear to be the oil and filter.
a) The handbook says the coolant, brake fluid and air filter should be changed after two years and every two years thereafter - given the mileage is this necessary for this car (no intention to take it on a track) and, if it is necessary, do I need to do all three or is one more important than the other?
b) The handbook also says that the diff and gearbox oils should be changed after four years. Will this wait until the next service in May 2011 or do I need to get it done sooner?
c) Regarding the cambelt, book says it needs changing at 66000 miles or seven years which seems a long time. What do Scoobynet members think is more realistic on this car given the low mileage?
Thank you