I have 2003 version of Amsterdam, Bruges & Brussels.
It states on pg. 27 the bus from Schiphol into Ams. takes 3hrs 20 min and train to Central Station 6hrs 20 min. I don't think this is correct, is it?
I think you are maybe misreading the book, Marianne? I think he means the bus runs 3 buses per hour and it takes 20 minutes and the train runs 6 trains per hour and takes 20 minutes.
It is a very short, easy train ride into Central Station - I do think you were looking at the information incorrectly. It's one of the easiest we've found - also Brussels is really easy and quick - did that on a layover between flights.
Schiphol Train station is situated directly below the airport. You can pick up a free baggage trolley from the platform. Via Schiphol Plaza, you can walk straight to the departure or arrival hall.