Key classes for group?Follow

All the key roles are still there...tank (fighter), healer (priest), DPS (mage and scout). Although that is the typical mix, you can have almost any mix. I've been in all caster groups - mages with pets. (No BST's, sorry)
If you plan on taking on an Epic mob or a tough zone, a healer is definately required.

Enchanters have not so much of an impact but can still mez adds, Breeze, and have some DPS. They may have a bigger role in Raids, but I can't speak to that.

In EQ2, there are a few significant things that are different:
- Locked encounters: When you enter combat, you and the mob/group are locked. Your max running speed is severly reduced, and no-one outside the encounter can cast into it or join. You can cast out of the encounter to pull more mobs or mez a possible add. So no power-leveing or kill-stealing. You can break the encounter and open it up to anyone, but all exp and loot is turned off.
- Agro: Mobs will not agro each other as they run to you, unless they are part of a linked group, and they will all come running anyway. And if you turn and run away, they will stop chasing you after a not-very-long distance, returning to their original point. So no more train-to-zone. You can effectively run across an entire zone, picking up and dropping many agro adds along the way.
- Solo: There is a significant amount of solo content in every zone. This makes the need for groups not so required anymore. However, solo mobs will give less loot than a tougher group mob.
- LFG: You could be LFG for hours, although healers seem to get picked up quicker. But with all the solo content (see above) there is almost no need to get a group. You will need a group for some instanced access zones or to take down big bosses. Or to get the good exp and good loot against group mobs, a group is required. You may hear that groups are forming, "...with 2 spots open, DPS prefered." Or, "...group seeks healer and tank for xxx mob."
- Quests: Hundreds of them. A great way to gain levels, items, money, maybe some furniture for your room. There is a nice quest log that sorts the quests and shows your progress and what you need to do next.
With up to 75 quests in your quest log, you'll always have some step in some quest to accomplish. You may happen across a group looking for more, that happen to be doing a step in a quest that you need. Jump in, get credit, give the celebratory "Gratz", and jump out.

Guilds always provide better ways to get groups, especially large guilds. Smaller guilds have joined together in alliances and created their own chat channels to help each other out.

Good luck

Thanks OBD. I think it was from posting a non-supportive response on the Alla front page under "Ad-free Week". All the negative replies were myteriously rated down within 24 hours of posting. :/
[tugging at my collar] I don't get no respect!