Our Rule: Minions Opportunity attacks/actions/reactions happen before the PC's attack is resolved.
Real Rule: All creatures Opportunity attacks/actions/reactions happen after the PC resolves his/her attack.
Reason: Sometimes this is the only opportunity a Minion has of inflicting damage on the PC's, and could potentially otherwise add nothing to the encounter.
Our Rule: Anyone with training in Stealth can attempt to become hidden with Cover or Concealment.
Real Rule: Everyone needs to have Superior Cover or Total Concealment to attempt to become hidden.
Reason: Gives some particular benefit to those who have spent the time to learn the skills necessary to be unnoticed.