Do you gain EXP for only one side of the fight, or do you continually unlock as you progress? Meaning, If I am playing as Security, do I still level up as Resistance, or do you have to bounce back and forth between them to level them accordingly for different fights? And do you gain different abilities for each "clan" or are the abilities universal per class in each clan?

The character is the same, and your always able to switch between Security and Resistance, so it's the exact same exp. As far as abilities go, yes they are the same for both factions as well.

You level 1 character, because it is stated that playing both campaigns will only level you to 14.
Someone get this man a Brink bible!

Edit Ninja'd, or is it Wraithed? :ninja:

You have one character who plays on resistance or security. The xp goes to this character regardless what side Youre on. You can have up to 10 characters and you Cant share xp. You have to indivudally build em

Thanks folks. I just started looking into this game today, so I am still learning how the gameplay is supposed to work. All in all it will be a pre-order by tomorrow from what I see so far.