I saw in a video that you can choose to either be the fight for the Ark or escape it. So if you choose either one, are you locked into that one or can you decide to switch to and play the other side with a new save? or do you beat the campaign with one side first and then you and play the other side? Any answers?

I think I heard once you choose it in the start you're locked into that one til you complete the campaign for that side

No, a character isn't locked to a faction. I remember reading it either in one of the reviews or in an FAQ. The developers were very clear on wanting people to be able to play the game how they wanted it.

No, you can play both campaigns without fear of being locked in the faction. You have choices in the main menu I believe its like this:

Campaign: Security Campaign/Resistance Campaign
Multiplayer: Join quick game/custom game/private game
Character: Create new character/Customize character/delete character
Options: Audio/Video/Controls/Credits

Thats just me though.

Correct, you are not locked to one side or the other of a faction.

No, you are able to play any mission on the campaign from the start as SD want people to understand both factions and what one they want to fight for.
You are able to play the last missions from the start if you want. :thumbsup: