Push bars will make the fire marshal happier, easier to open in an emergency "RUNNN!.....crap hold on gotta turn this..." Versus "RUNNNNN!!!" *push* "RUNNNN!!!"
And steel everything makes your life MUCH easier.
With fire retardant wall panels and a steel building, our town says we don't need a sprinkler. Not saying that you should count on it, but it definitely makes people happier. Just do everything geared towards making building and fire the happiest people ever and you'll have a great working relationship with them for a long time.