I've been dealing with gravel drives for most my life. The best way to spread it is to "tail gate" it out of the delivery truck. The driver will know how to do that. I usually put down a 4" "lift" (which is what a layer of something on a road is called). Any high or low spots can be worked with a rake.
Like one poster already said, running a car or truck back and forth seems to pack it as good as anything. Take it easy though. If you spin out just once, you've got to get out and repair the spot. A 4WD vehicle going nice and slow is the way to go. You can usually get most of the drive packed except for a foot or so down the middle. . . but that's good, because you can then rake that stuff out into the low spots, and there'll always be low spots.
I usally get what's called "crusher run" or "1 1/2 to dust." The crusher run is a little bit smaller, but not much.
Order enough to have some left over for a pile to be used later to fill in low spots, spread around walkways, driveway/road junctions, etc.