2000 Buick Regal Ignition Switch?

Thought I had a dead battery (weak/not cranking). After replacement, ALL Dash lights pulsating, when key cranked. Car not starting - when applyed e-brake and stepping on brake car would crank - car starts, then motor surges and stalls out when releasing e-brake, lights go back to pulsing. Went thru whole scenario, got car to run - then stopped at stop sign, applied turn signal and car stalls - dead now - back to pulsing lights until cranking all the way and evrything goes dead and won't start. I think it's ignition switch - where do I locate this? Under steering column (down by brake somewhere), or is it under horn/air bag assembly in steering wheel cover?