This year the front ensemble I am teaching is going to be amplified. I am all for this but lack experience in front ensemble amplification. From college marching band and something I found online, I have gathered that the following materials are necessary.

Microphones
Cables
Mixer
Power Source
Speakers

Is it better to be self powered our rely on power at the performance venue? How about the person running the mixer? Student or a staff member? I have seen a lot of groups hang the microphones from underneath the boards. Any thoughts on placement?

Some information about the group...it is a band of about 70 students with a front ensemble of around 7-8 people. No sound equipment is owned. Any recommendations on equipment? Thanks.

Whether power is provided or not should be mentioned in the materials you receive from a show host. If not, contact them prior to the show and ask. And don't wait 'til the day of the performance! (It may also be spelled out in your circuit's rules, possibly under the things show hosts are required to provide.)

When I used to work with an amplified pit way back when (96-98?), power was always provided by the show host, but that might vary by competition circuit. Whether the mixer needs to be run by a student or staff member may also vary by circuit. (I did the board myself.)

As for equipment... One thing I didn't see on your list is an amplifier. If you're not using powered speakers, don't forget an amp! (I found it convenient to avoid powered speakers because then you've only got one set of wires at each speaker to worry about.)