I try to keep the humidity no less than 60% in any of my tubs. For brooding females, I like the humidity to be between 60 and 80%.
This is my third year breeding balls and I've maternally incubated every clutch - 1 clutch my first year, 3 clutches my second year, and I'm anticipating 5 clutches for this year. I've not had any slugs yet, but if I saw any in a pile I would remove them (if the mother didn't push them out, herself).
When the eggs start pipping, the female doesn't do anything to harm them that I've seen. She just uncoils and the babies wander off after leaving their eggs. Once all the babies have left the nest, she leaves as well. I have a few pictures of some of my females checking out new hatchlings.
I have two other girls who are both going into a shed cycle simultaneously. I'm hoping this means I'll have two more clutches on the ground in the nearish future.