Couple car questions, please help

Hey i jus got a 97 ford taurus and i had a couple questions about it..first off, my airbag light is on..when i start the car it blinks a couple times, then either stays on or it will blink a couple times, go off for a couple seconds, then come on and stay on...any suggestions for that?..

and 2nd, the door handle was replaced on the car, and when i put my key in the lock cylinder it goes in right, but it wont turn/unlock...the other side works fine, but not the driver side..and suggestions about that?...

and last, when i accelerate, theres a little clunk, not really strong like a fully broken motor mount, but jus a little clunk but its noticable..do u think this is a tranny problem or jus a loose/worn motor mount?..also the car needs a tie-rod end, could this be the cause?

The clunk is probably a CV joint.

The door lock cylinder was possibly not replaced with a factory key pattern. It may be misaligned or a spring not in place, but I suggest getting a AAA membership and having them send a locksmith. They pay something like any price over $35. I lost my only key for a car and for $35 I got new keys, a new tumbler set put in my glove box to match the new keys, and four freshly cut keys.