There really shouldn't be any space between any fork and head tube, if there's more than a millimeter-ish gap, something's likley wrong. And yes, there should only be one set of bearings at the bottom of a head tube.
Is this your first headset install? You might want to consider taking your bike down to the LBS and having someone there do the headset installation while you watch and learn. Not worth risking damaging that beautiful frame with a botched headset install, you know?
This picture shows what the fork/head tube should look like: