RE: Ho do i calculate the time elapsed before a report is loaded.
You can drag items from the top pane into the aliases pane, and then rename them however you see fit. The structure of the aliases tree can be almost whatever you want, with one limitation: if you make one object a child of another, then it must actually be a descendant of that object in the main tree. You can also have multiple aliases for the same object.
Also, you may want to get into the habit of using the "Skip" button when you create new mappings. The effect of this button is exactly the same as the "OK" button, except that it will not create an alias. This leaves you free to create aliases only for the objects you want.