Can you answer some D&D 4th edition questions for me?

I’m familiar with the idea of role playing games, but I’ve never played Dungeons and Dragons. I’ve been invited to participate in a group that runs 4th edition. I payed the $10 to use the wizards.com character generator and I’m making a new character right now.

Some questions:
1. Can you use a minor action while using a move action? There is a minor action that allows a character to mark an enemy within 2 squares. Can I mark the enemy as I move past or do I have to stop within 2 squares to use the action?

2. Can a character be concealed by standing behind other characters?

3. A spell damages an enemy if it moves away from a character. Is that only if the enemy moves away by choice, or is that also triggered by someone else’s action moves the enemy?

4. Do you have any class/race suggestions for me? Apparently most of the group is “strikers”.

5. Do you have some references/websites that you’d recommend I look at?