Create character and choose one of the four types: Hunter, Ranger, Force, Vanguard/Braver
Once in Clad6, there's an NPC that give you the following options:
* Change class type (for a small fee)
* Allocate weapons for the chosen class type (the higher the level, more weapons you can equip in terms of C to S rank)
* Choose type abilities; as you level up your type class you will gain abilities, here's a list
http://psp2.psupedia.info/Type_abilities
You level the type class up via missions, at the end you'll be receiving mission points for them.
You can equip any weapon you want, just that other classes will benefit more e.g. Ranged weapons on a ranger or Swords on a Hunter.
This is also due to limitations on the PA skills for each class;
Force users can use upto LV30 technics while hunter/ranger are limited to LV15 and Vanguard/Braver to LV20, etc.
So in short, it's a free for all for what you wanna do...
The abilities, roles and such will depend on your choosing.
Edit:
The type abilities that have been unlocked via a class can be used for any class of choosing.
You start off with 4 slots per class, but that'll extend to a max of 8 slots as you progress for abilities.
This is what makes your character unique, it makes you specialize... makes you special @_@