Good luck and best wishes in a challenging position! A few thoughts:
*is there any way to create Professional Learning Committees (or something less formal – I just call them “teaching teams” within the department? This can be a good way to get teachers working together in small groups.
*there are a lot of good resources online for “protocols” to follow in some department meetings, which provide a structure for helping to prevent a few individuals from dominating the discussion. They seem cheesy at first, but my team bought it and it was helpful.
*the best thing I ever did as department chair was convince our admin to pay for a day-long “retreat” (we went to a local hotel) and had a full day of conversation. It took a lot of time to plan and structure so that it was meaningful, but we got a lot out of it.
All my best,