Any tips on insurance requirements? What should we provide, what
should we charge for? Any mistakes you may have made that you can
save us from repeating?

Somewhere on the FAA website there is a document that pertains to
"aerobatic waivers". This document will proscribe the requirements for
things such as deadlines, showlines, crowdlines, etc.
Contact the International Council of Air Shows (ICAS) (they have a
website, http://www.icashq.org/). I am certain they will be more than
happy to help and advise you.
They may even have a checklist for sponsors.