Hi Kristine and welcome to WKC.
It's not the Vortex per se that would cause food to burn, but rather whatever heat it makes and for how long. I'm not trying to be flippant, but just noting that you do have control over how much charcoal goes into it and where your bottom and top vents are.
The presence or absence of the center part of the grill shouldn't affect what happens vis-a-vis heat transfer too much, I don't think.
Foil is a good idea in my opinion. Keeps the grill a little cleaner and helps direct incoming airflow from beneath where it needs to go: into the vortex.
Bone-in chicken parts can take the heat, so uncover, and watch them every once in a while and let 'r rip.
So ... practice? (Others will offer actual, practical answers soon.)