As for floating objects, there are 2 reasons I could think of that may be the problem. If you had placed objects while making the map and then later on decided to change the size, either the length, width, or height, that would cause the already placed objects to either sink, float, or be slightly moved due to the change in size. If that was not the case, while you were placing objects in the map, if you placed them from like, a bird's eye view or in some view that was far away from the ground, your objects could have been placed "floating" without you noticing. Also, if objects are placed half on a hill or dip in the ground, half of them can sometimes appear to be floating. If you go back into the map maker, you can zoom in close to your placed objects to see if they're slightly floating. If they are you can adjust the Z coordinate I believe to fix that. I hope that helped c: