I think much of your troubles are Fire related. Give that KBB to your BIL and go buy some lump, all that waiting for the smoke to clear will vanish it burns hotter, longer & cleaner. I would get rid of them baskets to and just build your fire on one side. Cover the remaining area of the coal grate with HD foil so it forms a seal at the kettle edge. this will allow you to have complete control over the fire: fire is a bottom feeder it sucks air in at the bottom and releases its energy out the top in the form of heat & smoke. You control the air you control the fire.
I cook hotter than most 275 -325. Chuck roast need s to go higher than 200 it to reach that magic place, more like 210. A chuck Roast is almost like cooking a Brisket flat they have allot in common. Tight grain structure lack of surface fat and lean( not much marbling) Cuts like this do better at higher temps to prevent drying out. Once the surface dries out the rest will be close behind. I typically go 3 hrs and either set up a braise in a hot tub or wrap in BP and go to probe tender. I'm a S&P rub on beef believer as it lets the beef flavor shine.