Is it worth completing Dragon Age Origins before playing Dragon Age 2

"Blue smoke" sounds like the spell cleansing aura. Check your mages to see if any of them have it active.

As mentioned in another answer, they likely cast the spell because someone in the party was injured. However, my experience is that only the initial casting of the spell removes injuries, not the persistent "aura" effect which heals hit points. So if you see the aura and are still injured, you need to turn off the aura, wait for the cooldown, then cast it again with your injured party member in range in order for it to remove the injury.

My copy came along with a card with a code for the The Stone Prisoner/Shale DLC pack which retails for $15. The same card also had a code for Blood Dragon Armor in Mass Effect 2.

The DLC itself is pretty short, but the character you can add to your party isn't bad. In my opinion, it's not worth $15 to buy yourself, but you're not missing out on a whole lot.