As for the stems, they are thinner than the bud so they dry out first. Usually the smaller stems snap first, then the larger ones, then the bud is too dry. I usually aim for right then.. when the smaller ones are snapping, and the larger ones are still bending. By that time the buds usually feel dry on the outside.
As for getting a little moisture back into the buds? I have a little tiny jar, probably 1" in diameter and 3" tall. I will put a small amount of water in the jar, like 1/8 to 1/4" and then place it in the curing container. Come back after a day and the water is magically gone from the jar. If it needs more, I add more but usually thats enough to get a little "bounce" back into the buds.
I don't like using lettuce or rinds because if I forget about it for a little too long it tends to get stinky and messes up the smell of the nice bud.