go to the group elements that the layer is in and change the height (h="?") to either the layer height or sumthing like 500 or sumthing. also if u really wanted the answer you could have searched it with the forum search tool...its only come up about a million times.
yes. but i geuss his problem is the w and hight of the goupdef. But in fact wa3 works like PS. You can put the layer one over the other. It is pretty cool cause you can just use the layers and how they are placed just like in your psd file