Would shaving the edge of the bill on say a Bomber or Bandit crankbait with a file change the action or depth of the lure? I've heard of people doing it, just curious if it would do more harm than good, and how precise it would have to be or if the lure would run all goofy.

If you shave the edges of your crank bait you have to take off an even amount on each side or it will not run as straight as you would want. What it does when you shave the edges is it takes some of the wobble out of the crank bait. If you take some off the bottom it won't run as deep. Just take your time and practice on some old or cheaper ones until you figure it out.