BI is considered pretty competitive, and admissions there works the same as everywhere else. Ideally you have good scores, letters, grades, and some research. There are residents there that have very little if any research, but they stand out in other ways - and vice versa. There's probably not a specific score cutoff, but your data will be compared relative to everyone else who applies. I'm not a grad of their program but I can promise it's not rocket science.
Most programs like this consider auditions rotations helpful if you already have a pretty good application and you make a good impression in person. If you're not already someone they would consider competitive for their program, it probably won't matter.