Lots of changes. I'll outline the things you just said quickly:
1.) Skills are pretty much based on what weapon you have. Switch your weapon and you switch your active skillset. Limits of 5 weapon skills, 4 utility skills, and 1 elite skill.
2.) As you use a weapon more and more skills unlock over time. They are supposed to unlock fairly quickly though, so you won't be grinding for the best of them.
3.) Traits are basically "perks" that will require completion of challenges throughout the world. That's pretty much like what you were talking about.
4.) Classes in GW2:
Warrior - Same as before, can effectively wield a bow and rifle though.
Thief - Cloak and Dagger, assassinish.
Ranger - Same old same old, gets an axe though. Pets exist.
Engineer - Brand new. Access to turret and barricades, uses a rifle as a main weapon. Cannot switch weapons mid-battle, instead switches his utilities via kits. Has access to a flamethrower.
Mesmer - Same old, uses a sword as well now, summons images that attack your foes.
Necromaner - Probably the closest to the old class. You can sacrifice any of your minions to commit an effect.
Guardian - Warrior focusing on buffing and defense. More tankish, but can still deal damage.
Elementalist - You know this one by now. Four style. Air - single target DPS, Water - Healer, Earth - Tank, Fire - AoE DPS. Can't change weapons mid battle I believe, or at least elements.
All of the classes ARE significantly different from GW however, so I'd still give them a looksie. Guildwars2.com.
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big it is. I mean, you may think it's a long way down the road to the chemist, but
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