Hi,
We rolled out a similar set of iPad Air 2s recently, so here’s what worked for us:
Charging trolley: Look at LocknCharge or Zioxi both do neat 16–20 bay units with built-in cable management.
Apps: Best to use Apple School Manager with an MDM (like Jamf School or Mosyle) saves you having to plug each iPad in.
Promethean board: Most newer panels support screen sharing directly, so you can mirror without an Apple TV just check firmware and Wi-Fi setup.
Printing: Go with AirPrint-ready printers if you can; otherwise, HP Smart or PaperCut apps work well.
Saving work: Cloud storage is simplest Google Drive or OneDrive depending on what the school already uses.
Also, keep everything tidy we used Tool box foam inserts inside the trolley to organise cables, chargers and small accessories, and it’s been a huge help.