Jamz;
You can go either of two ways with the neck size - deprime question. Dillon offers a neck size only die for the .30-06, or, back off the present die until it's just sizing the neck & screw in the decapper till it pushes out the spent primer.
OK, how to tell how far to back off the sizer die? Go to NAPA & get the small tube of Permatex Prussian Blue. It's a mechanic's, machinist's marking dye. Put a small, repeat small, amount on the neck & shoulder of a test case. Back off the sizer die two full turns. Remember, you still need to lube the neck, and go ahead & size the test case. You should easily be able to see how far down the neck the die contacted the case. Adjust until it's sizing to just above the shoulder radius. You don't want to push the shoulder back, so don't try for the last .001", it's OK to be visibly short of where the neck flares out to the shoulder.
As a suggestion, also get the Dillon .30-06 case gage, part # C50-12679. It's an excellent tool, easy to use, & will take a lot of headache out of determining as to whether or not you got it right. Well worth the $18.95 price tag.
900F