Regarding exhaust vents, everytime I've done chicken I found my dome lid exhaust not large enough to run temps up around 350F. I had to prop the lid ajar to allow the drum to breathe more efficiently. Therefore, I'm thinking about adding another adjustable vent on the lid for high temp cooks.
I know this is one mod that some 22" WSM users make. They add a second daisy wheel on the lid.
Here's a shot from tonight's cook.