Dale, old rule of thumb, neck size down as far as the diameter of the bullet. Only time I don't, is if the gun has such a deep throat, and the bullet will be seated out so far as not to be entirely in the case to use the necked down portion. Then I'll just neck size the top.(such was the case with the 7mmSuperMag.)
Be real careful about not lubing neck's. If you get a case stuck, which is unlikely, but can happen, you'll play hell getting it out without ruining the case.
I would suggest Imperial sizing die wax. Just a touch on your finger, and you can put enough on to lube 4-6 cases.
Lloyd, Redding makes carbide size buttons for .22 thru .30 cal. And, I believe they'll fit on some RCBS dies. Certain calibers will not. gypsyman