Airstream,
To properly neck size, yes, it does call for a separate die. Personally, I strongly advise against neck sizing as a regular practice, even if you're using it in the same die. Full length will do just fine on new brass (and you should,'t feel much resistance at all) but the main point is just to make sure you're rounding out the necks and uniforming the neck tension. F/L sizing will accomplish that. You might want to look into a headspace gage, such as the Wilson, an RCBS Precision Mic or a Redding Instant Indicator so you're not sizing the brass any more than you need to. That's the real key to living happily ever after with full length sizing; not overworking the brass, and not bumping the shoulder more than needed to allow free chambering.