1. Roleplaying is for going into the world and leveling up your character, fighting, doing missions, doing quests, etc.
PvP-Only, is exactly that. It means you can only do Player vs. Player (fighting other players) on this type of character.
^ Like PvP-Only characters, Roleplayer (or PvE) characters can do PvP too.
I'd personally do Roleplaying, and once you get to lvl 20 or so, PvP if you'd like. OR, if you just want to fight other characters, then just make a PvP Character.
2. These are basically the "classes" in Guild Wars. Pick one that reflects your style of gameplay. Also, you can have a PRIMARY profession, and a SECONDARY profession.
Warrior: Obviously, a warrior. Primary weapons are swords, axes, and hammers (you can use a shield with swords and axes, hammers are two-handed). This class is a front liner and does lots of damage and takes hits.
Ranger: My personal favorite. Wields a bow and can have a companion (pet) that helps attack. Mainly for support and some damage, good with interrupts and condition spreading.
Monk: Basically the main healer in Guild Wars. All casters mainly use a staff, or a wand and focus.
Necromancer: Master of the dead and undead. Can create undead minions, transfer the life from monsters/humans to themselves, and use curses to do damage.
Mesmer: I don't know a ton about this class, and it's probably the most underplayed, but..... Master of illusions and interruptions. Has some damage skills based off of energy, things like that
Elementalist: Basically the mage, or magician, of Guild Wars. Master of the elements of fire, water, earth, and air. Deals tons of damage with their spells. They also have an extremely large energy pool.
Well, that's pretty much it.
