1) When the compost is uniform in texture, has a rich earthy smell, and none of the original ingredients are recognizable.

2) Probably. It depends on how much nitrogen you add and how finished the compost really is.

3) I would just layer it on top, about an inch thick at one feeding. You could go deeper, depending on how often you feed.

my worm love it, my hot compost is made from horse manure/ bedding and table scraps and yard waste. the bedding has lots of wood chips that soak up the good stuff well. After a batch is done i like to throw a good bucket of partially composted stuff that didn;t go through the first screen in the worm bin.

ron