Is there any possible way you will be able to either have multiple save files or will there be any way at all for you switch from security and resistance? what if you choose security and find out "man, this clothes svck I wish I would have picked resistance" is there any going to be anything to solve things like this? Also because in the videos it seemed as if the guns look gritter on resistance and "newer" on security so please if anyone knows please share!

Each character is on both teams, you can change how he looks like for each team.
You have 16(?) character slots too in addition.

You can have up to 16 different characters, and every single one of them play both factions. This isn't WoW - you aren't locked into one faction. You can play either one, and get customization options for both. Also, the guns do look and sound different for each side - Resistance guns are beat up looking and sound it as well, and Security weapons look and sound new and well maintained.

Thanks guys. However, now I find my excitement for this game increasing from this...help me...it needs to come out NOW, all other shooters on the market seem boring Perk systems and only weapon mods have caused all shooters to seem bland when compared to brink

It might be something to do with brink not putting constraints on the player, instead jsut allowing the players to play the game the way they want to.
Many singleplayer games are already like this, but I can't really think of any MP games like Brink except Brink.

Concerning your questions about the characters, I suggest you read this: http://www.gamesas.com/index.php?/topic/1154126-unofficial-brink-faq/page__pid__16913615#entry16913615

What you say about the guns is correct. The guns have a different sound and look on each side. For the sake of balance they have the same stats though.

If you still have questions or if you want all information, then you should go to this site: http://www.fragworld.org/frag/community-blogs/brink-info-pt-1-story-gameplay-smart-classes-and-objectives.html

Edit: I was too slow

If only other MPs cared about the gamer :/

Crysis 2

They're also the same guns. The Resistance has used, rusty ones, whereas the Security use clean and newer ones.