1. Left mouse drag? Instead of Right Click+D for delete you could have a delete button, which deletes the last moon you placed or moved?
2. Hints are definitely a good idea, but I think some people might want to try to progress without using them. Instead of rearranging levels another suggestion might be, if you complete x levels of mechanic area y, you also unlock the first level of mechanic area z. I'm thinking of something like Mario 64, where I think there are 6 stars available in the first world area. However I think you only need 2 or 3 to unlock the second world area.
