I have some insight on this. I was a Willie in 2008 and 2009. It was interesting. I was a freshman/sophomore those years. My freshman year there was only 1 returning Willie and I was one of 6 new guys, so there were 7 Willies that year. Sounds like a ton but we did every sporting event: football, M/W bbal, vball, baseball, plus weddings, birthday parties, athletic booster events, open house, enrollment/orientation, etc. So we were all fairly busy.
My first year was a blast. Our "boss" was the marketing branch of the athletic department, and with that we were able to be pretty creative with skits and such. My favorite skit was the first year when Willie beat Micheal Phelps olympic record for golds by winning like 20 different events, it was the home opener vs North Texas, and I was actually the guy tackled at midfield after stealing Willie's medals (the guy the used to get tackled was always another Willie). I think I got a mild concussion from it but it was worth it (glad I don't have a seizure disorder
)
The second year we were transferred over to the cheer team and it was not nearly as fun. We had less access to the pregame schedule, skits where cut down, we had to go to cheer practices sometimes, it was a drag. I got cut after 2 years bc I discovered beer/got too fat/dipped out on a lot of stuff the 2nd year to focus on grades and partying. Was a little butt hurt at first but in retrospect I think it was good for me.
On the point of a black Willie, the answer I got a lot when I asked (I don't think any tried out my 2 years) was that there is only 1 Willie, so all the Willie's needed to look similar. I always thought that was dumb/racist, esp since there was a 5'8" guy and a 6'3" guy in the group when I was doing it. But they take that pretty seriously, Willie could never be at two events at the same time.
Anyway if you have any questions about it, I'd be happy to answer.