From what I can see in the photo the first thing you need is a side table. After that, for the kettle, I would say Slow N Sear. For you I would say hot gloves, (maybe welders gloves), instant read like Thermapen, also a wired or wireless thermometer (because you don't want to be lifting that lid a lot), 1 set of 12-13" tongs for food and 1 set of 17"ish tongs for charcoal.
The Slow N Sear is expensive but it is also my number one kettle tool; it never leaves my grill.