Problems with 2001 GMC Sierra 1500 POWER TRAIN

Was about to go shopping for christmas gifts, stepped on brake at top of court and the peddle went to floor. not just loss of hydros full on brake malfunction , no brakes at all. i live in new york and truck was purchased from connecticut. decided to make left turn and missed getting hit by 18 wheeler by inches. i am lucky to be alive to be typing this now, no thanks to gm. no warning lights nothing at all just no brakes. to add emergency brake did not work. *tr

It started with the fuel gauge fluctuating between full and empty with a full tank of gas and the abs and brake light on dash lighting up for apparently no reason. then it started giving me trouble starting and making a weird whining noise. i checked all the fluid levels and fuses, everything was ok. i was at the camp(middle of nowhere) at night when i noticed that there were sparks coming from around the area of the starter when my husband tried to start it.(it just happened to be dark and i was sitting with a view of the right wheel well) i checked the wires and found what might have been a break in the insulation, taped it and the sparks quit. had no choice but to drive it home the next day as there was no phone service. started right up , and drove fine, except for the low whinny noise that no one could pinpoint. i was almost home when the transmission started to slip. i brought it to our mechanic who replaced the transmission but none of us can figure out what the devil is causing the electrical problems. before the transmission went out the tow/ haul button didn't do any thing, now the light actually comes on-when it feels like it,but i can't get it to go off. the gas gauge is still acting nuts and the abs and brake light still come and go. please post instructions for troubleshooting this thing! *tr