I'm confused on one thing. When I am writing a cover letter to a certain department at an agency, and there are more than one agent(s) in that department, who would I address it to in my letter???

Here's a thread that should help.
http://bbs.backstage.com/eve/forums/a/tpc/f/8011031/m/92710675

This is a great question and since I've been an agent for over ten years, I think I can help you out.

The key is to pick someone, anyone. You have to address it to a specific person or your submission will end up getting tossed.

Now here's the thing. Do not address it to more than one agent. Trust me - this is a bad move. Agents make more money based on who they sign. So let's say you submit to two agents and they both want to bring you in. Now what? They're not going to fight over you so the odds are they'll say forget the whole thing.

So pick one agent, submit to that person, and wait at least two weeks. If you don't get a response, then feel free to submit to a different agent.

Hope this helps and good luck!

Thank you Mominbiz for the great thread and a BIG thank you to Secret Agent Man for the advice! It definitely helped!