Welcome to the forum and congratulations on the new Kamado Joe! Controlling the temperature will get easier with time. The Kamado is a big hunk of ceramic, when it gets hot it takes a lot of time to bring it back down so start shutting the vents down early, like 30F away from your target temperature. There are some good videos out there that show the technique. Best of luck and enjoy the new grill!
When I saw that sauce I knew you were from NY. My favorite sauce is from NY too and I live in GA. (a friend from NY keeps me stocked up).
It's like a cross between a vinegar based sauce and a tomato based sauce.
I assume thats a mustard based Carolina BBQ sauce. I'd never tried (knowingly) mustard based sauce until a couple of years ago. Man, its really good! I'll get either the Harris Teeter brand or Sweet Baby Rays, love it on chicken.
I'm not loyal to any particular sauce though. Often the SBR hickory and brown sugar, or HT branded sauce, but I could come home with anything.