OK here comes the "standard" speech...
Any character playing any class will be in demand if you play him well. The big secret here is to learn the role of your class and to play that role as well as it can be played. The big trick to that is to play a class you love to play. Enjoying everything about the class will give you an investment in their success. And an invested player is never bored!
If you want to play a stealthy DPSer try either Assassin or one of the rogues (brigand or swashy). Heck, try out all three of them!
In the early game you should focus on learning the basic mechanics of the game and your class then learning what your class does best and how they do it by studying each of your spell lines and how the different spells fit into those lines.
As you level, you should concentrate on keeping your armor and weapons up to date and also improving your spells by upgrading the ones you use the most. Also try and focus on game mechanics that are unique to your class... can you use poisons? Can you use a bow? Should you choose a different thrown weapon? Two hander or dual wield? Shield or no shield? Crush, slash or pierce? There are tons of choices to be made with every character. Study the options and you will learn what works best for you.
There is no set time to join a guild. Talk to some of the guilds who are recruiting on your server and look for a *good fit* between the guild and your play style. Are they (mostly) located in the same time zone as you are? Are they a casual family guild or hard core raiders? (And how does that match up with you?)
Switching servers is not a casual move. Yes it does cost $50 per character and so is not to be undertaken lightly. The good news is that at (say) level 20, it's easier to level up a new character then move one! (As you become more familiar with the game you'll be able to slam through the first 20 levels or so in a few hours.)
And finally, don't worry about a character being in short supply. The best way to be needed in game is to be very, very good at what you do.
Welcome to MMOs and welcome to EQ2. Good luck and feel free to come here and ask the community anything you want to learn.
Edited, May 21st 2008 4:37pm by OldBlueDragon