Smith910--You certainly are asking important questions! A good source to read, whether for newbie or oldster, which has a
LOT of excellent how-to and more importantly why-and-why-not-to info, is
The ABC's of Reloading put out by Krause Publishing. They are in the 7th edition; the 6th is good too if you run across one. Get it @ yr local sptg gds sto, gun sho, the I'net, or order from the publisher at
www.krause.com
As to rifle sizing dies, you may need both a FL (full-length) and a neck sizing die. The neck-sizing die saves wear and tear on the cases, and is useful for sizing just the necks of cases you fired in a bolt action gun which are going back in that same gun. Lee's collet neck sizing die is IMHO as good as it gets. Now, for pick-up brass, or for loading ammo for a self-loader, a pump, or a lever gun, you need to FL size the cases every time, since pickups may be any old size, and for your non-bolt guns, the case gets sprung out enough that it needs the FL treatment every time around.
Even with new-bought so-called "virgin" brass, I check to make sure it all chambers, then run it through the neck-sizing die.
Rifle dies generally come 2-to-a-set, either a FL or a neck sizer, and a bullet seater. Pistol dies generally come in 3's, a FL sizer, a mouth belling die, and a bullet seater. If you order from Lee directly, they will gladly make up whatever set you specify, so for any rifle cartridge they stock, you could get a Collet Neck die, a FL sizing die, and a bullet seater, all @ once. You hear different opinions about some Lee equipment, but AFAIK, nobody knocks their dies.