Cobalt SS Network - CEL, airbag, etc.

Hey guys,

So, I have decided that it was time to fix my car, come spring. I've had CEL's and whatnot for quite awhile now and have never done anything about it. They'll eventually reset and turn off. But I want to actually fix the issues. I have an Injen CAI, GMPP Performance catback, and a Shift Plus on my car currently. Aside from that, everything engine-wise is a stock 2.4. I've gotten CEL's every time I've done anything engine-wise, such as: do anything with the intake, install my exhaust, etc. The car still runs perfectly fine, but the CEL just shows up. I read another post that that doesn't always necessarily mean there's a problem. I've never gone to get it scanned, and I will be soon. But I just don't want to go to the dealer and have them charge me $500 for something I can fix myself for next-to-nothing.

I also have the infamous key stuck in the ignition from my auto shifter button malfunctioning. I'm out of warranty, but will the dealer fix this for free? If not, how much?

And after I added my Ion Recaro seats, my airbag light comes on every time I turn the car on. It didn't for awhile, but now it does. I don't have the actual airbag sensor IN the seat yet, but it's plugged in. I figured that'd eliminate the warning light. It didn't.

Lastly, is there a way to basically "re-flash" the ECU to eliminate all CEL's and whatnot? If so, where and how much? I will be getting the car tuned come summer as well. Will this be able to eliminate any of these problems as well?

Thanks!!!