Yes, the SCHC app is daunting but I’m glad to hear she completed it. My D is a 2nd year there and when she applied, there were 5 or 6 essays! We are also 10 hours away (Phila suburbs) and it’s not a bad drive. Campus is urban but Columbia is a manageable size and the campus, although it has shuttles, is quite walkable.
I don’t know much about marching band except that football is screamingly popular. Your D might be eligible for additional merit $ for that; you may want to check with the Carolina Music Dept.