I’m not sure what the piece is in the second photo?
But for the wood placement, I also have hot spots and i try to place wood around that. But there’s a few ways to go about this - I try to place my chunks parallel to the wood box so that the chunk is not over one of the holes. This seems to help not allow the chuck to turn to ash. You can also use a foil boat to help with this as well. Just take some foil, punch some small holes and place it on the bottom of the box then your wood chuck. You can do this for each area, or just the hot spots. I really only use foil when I use wood chips.
That’s my experience. Others will post on their experience as well.