1.For the moonlight, they plan to have a person walk in holding a lantern, so that the light from the lantern would imitate moonlight. On the other hand for the wall, they would have a person standing there with his hands stretched, and make his fingers into an "O" shape, so that would be the crack they talk through.
2.When Bottom reappears, everyone runs off because Puck has mischievously turned Bottom's head into a donkey.
3.Puck plans to turn into something bad and scary and scare every single one of the actors separately, using different kinds of scariness or movements.
4.Bottom reacts kind of weirdly, in the way that he makes fun of the four fairies' names, and then says that Titania has a strange sense of compassion.