sooo, what's the major difference between a gladiator and a Paladin? When do I get Paladin armor?
Paladin is the "promoted" class of gladiator (level 30+) and "secondary" conjurer (15+). You'll eventually get free gear once you hit level 45 that is specific to your class. Otherwise just pick up whatever is an upgrade from quests. Don't spend gil/seals on low level gear.
http://ffxiv.gamerescape.com/wiki/Paladin