Cams spin at half the rate of the crank.
Duration is expressed in crank degrees. You can get 330 degree cams for drag motors and so on.
I would imagine the 420 and 450 are indeed lift figures.
Cams very intresting things, lobe seperation angles, lift, duration, base circles, ramp, flank, nose and all sorts of other terms.
The port castings usually have a step in them due to the way they are cast, bits of sand that form it fall away and leave a sharp turn at the short turn radius.
Chris