Patrick, I agree they are being cooked. I think full sun at your temperatures for those young plants is a bit too much. Certainly the spots on the leaves are burn.
Your soil/perlite ratio should be perfect. Packing the soil too tight may compact it too much. It is essential that the soil drains well, although at your temperatures I cannot imagine it would stay wet too long. That Miracle Grow potting mix is not by any chance one that has the water crystals in it??
I think the rocks are ok but do move them just an inch or so away from the trunk.
The sticks without leaves - are they unrooted cuttings?
