Welcome to SMF!
The butts and loins are large hunks of meat that you smoke till done. Just like a brisket.
They are more forgiving than ribs or chicken where it doesn't take long to go from done to over cooked.
i have used the MES since they came out with the first MES 40 ' and i have found that the first thing you need to do is buy a couple of good remote thermos that you can test in boiling water for accuracy,
The ones in the mes are known to be anywhere from 0 - 20 degrees off in either direction.
Once you have something known to compare the read outs to then you can dial in the cooking temps on your unit,
The one i have now reads 15 degrees higher than it actually is. So i know to run my temp at 250 to get a 235 cooking temp.
I would use the 3-2-1 method of cooking ribs till you get the hang of it .
Chicken is great coming out of the MES as long as you either use a grill / broiler or fryer to crisp up the skin after smoking it. The unit will not reach high enough temps to have crispy skin .