You should keep the cabinet at 80F or below otherwise you might end up with melted or deformed cheese.
I go for 2 hours with apple, maple, or alder.
You will need to put ice in the cabinet especially if you are not using a cold smoke adapter of some sort. The puck burner will raise the cabinet temp up to 150F by itself.
Apple will be fine. After the cheese is smoked wipe it dry then vac seal and place in the fridge for at least a month to mellow before trying.