possible petroleum contamination or a failed master cyl/abs if applicable
Yes. Otherwise if the backbrakes locked abs would be useless.
Having ABS does not change how you bleed the brakes. Bleed them as you would if it did not have ABS.
If trailer brakes are locked up it is probably because they have not been used in some time or need servicing. Sometimes rapping on the back of the brake assembly LIGHTLY may release them but it would be better to remove the wheels and brake drums and service them.
None of the landing wheels would not be locked in any sense of the word other than at the gate when the brakes are fully applied.
Check you brake fluid and lines. It may be as simple as bleeding your brakes.
It depends on whether you need new brake pads or your brakes completely replaced. New brake pads and labor would probably run about $100 but completely new brakes would probably be a few hundred.
at a guess the brakes have still got air in the system and need bleeding properly
Bad brake booster.
An 03 would have them all around.
same way you would on any other vehicle
Best bet would be your friendly local Chevy dealer parts and service dept.
Usually the fuse is going bad.