raid - dungeon challenge for 10 players, hard and take a lot of organisation and training to win, almost like a military operation.
Wizard's Tower - floating structure relocated by its wizard owner from its original location (I don't know if it was always floating or if it's actually a raid dungeon, the wiki page would say if it is, I thought, so ).
balance - keeping the gameplay, professions’ skills and weapons, etc from being over- or underpowered, too hard or too easy.
main - the character or profession you play most often (others being alts).
mini - mini versions of game characters you can have as mascots running around with you.
elite specialization - once you’ve reached the highest level, this expands on your profession with more skills and a new weapon.
legendary - one of the highest-quality weapons or armour (or backpack

) you can craft/have made for you once you've reached the highest level.
world v world - capture-the-castle battles for potentially hundreds of players from three different servers.
patch note - notes about what’s been patched/updated/fixed.
Dulfy - runs a very comprehensive fansite dulfy.net
Ogden’s hammer guy - I don't know who the guy was, but Ogden is a dwarf who helps the scholars and from googling all this I've discovered "By Ogden's Hammer!" is a phrase some characters use especially reacting to how much things cost from in-game merchants.
Scarlet - Sylvari villain.
The Mists - “the oldest thing in existence, the proto-reality that exists between the worlds, constituting the fabric of time and space that connects the multiverse together".
Kasmeer whose mini is more expensive - a Human Mesmer, I remember my human character working with her in part of a quest.
Living World - large updates of game content to bring the game to life as a changing world, some of the events affect the world permanently.
I didn't catch who or what Dara is, if that's how you spell it.
When they referred to "east... expansion" that's about Cantha not being in the next expansion as it was based on Asia in GW1.