I just bought a 1999 Audi A4 1.8T.
It has just over 100k miles on it.

..and now it has a few issues.

I have 3 engine codes that came up today:

P0018 (engine coolant temp (ECT) circuit high)
P1128 (Long term fuel trim B1 system too lean)
P1136 (Long term fuel trim add. Fuel B1 system too lean)

I am curious if these are simple fixes, or if it's going to cost me.

Also, my airbag light is on, and the car has never been in a wreck, and the airbags have never deployed.

And my final problem, the ABS light is on, and the brake light is flashing.
The brakes are working just fine as of now, and the guy I bought it from said it was just a sensor.

Thanks for any help, I really appreciate it, and hope to enjoy the new car.