Pool Table Levelers - Level Your Pool Table Without Repeated Lifting

Does this raise the table higher than allowed by professional rules?

That keeps these at the desired height? Is there a locking brake? Will the balls dent the ramps after awhile so future adjustment is difficult?

Can Flatjax be used on a three piece slate table?

I have a pool table that is outdoors (Roof are but open) would these rust with water contact?