1.  Yes.  But it does take special primers:  CCI No. 35 I think at the 50 BMG ones.  And not all presses have the height for 50 BMG.
2.  50 BMG or in general?  In either case the reloading press arm is cammed so it multiplies the force a bunch at the top of the ram stroke.  Not that much effort is really needed using a press.
3.  No.  LC = Lake City, 13 = year 2013.  A magnet is your best friend if looking for steel cores