The following is a work in progress. Not all of it is represented here but I am open to constructive suggestions made by anyone who should happen to find and read this post.

It begins with the principles sitting around an abba drum... Or the leader sitting and beating it and as the principles are ready to join they come in and begin to play in unison. This will continue through an invitation to the Holy Spirit to lead, to invoke a spirit of unity and to free those in attendance to pray and dance.
The abba is continuing throughout this period.
Then the principles, again at the leading of the spirit, will move to there own kits or hand-drums and begin to play in submission to the abba for a time and then all will fall silent for a moment.
The silence will be broken by a principle hearing a spirit led beat whether in exultation and hallel or a call to arms. From this point on it's for the people to play what they feel in their heart. Dancers dance, flaggers flag, intercessors crunch...
I must find a signal for when something specific needs to be done in a unison

Cacophony is out, I think. Unity for the city is a major battle in this endeavor- dynamics, tempo, rhythm are going to be the greatest weapons in our hands during this event.

There is much that I have yet to consider, but these bits need, I believe, to be held on to.