Commanding their own brass band?

Hello everybody.

“…Thirty minutes before the heated battle, Jingu Stadium is buzzing

with anticipation and emotion. Tens of thousands of fans have been

streaming into the great stadium around the field since early this

morning, and at this point there’s barely room to stand. The cheering

squads for each school have occupied their sections along the infield and

outfield and jammed their seats to overflowing. With Keio on the third-

base side and Waseda on the first-base side, each commanding their own

brass band, they have been sounding off fiercely since before the

match…”

Would you please answer my three questions?

First, in buzzing with anticipation and emotion, what does anticipation mean? Does it mean the fans were guessing who would win?

What does commanding mean in line 7? Does it mean controlling or having their own brass band?

And what does they refer to? The cheering squads?

I really appreciate you for the help ??