Hi again, @lemon! Two things:
(1) To address your first question, do you move your cookies as the icing is drying? This can sometimes disrupt the icing that has begun to set on the surface, leaving cracks in it. I don't ever move mine when the icing is wet unless the cookies are fully supported by a heavy-duty cookie sheet or other inflexible surface. If the surface bends, this can also disrupt the icing. Send a picture of your trouble if you can, because if this is not the issue, a picture may help others troubleshoot for you.
(2) I moved your second question about a nice icing recipe to another forum topic, as it is a distinct question. It's best only to ask ONE question per topic so that topics can be easily searched and found later. Here's the link to that new topic: http://cookieconnection.juliau...ng-recipe-with-shine
Thanks!