1 way of finding where an icon is at is to right click on it go to Send to> Desktop (create shortcut)
Right click on the shortcut go to Properties
Go to the Shortcut tab and click on the Change Icon button
In most cases it will show you where it is located
For the icon in the removable media you can create a AutoRun.inf file (If it does not have one if it does just modify it) and put it and a icon in the removable media and you will get the icon you want.
Open notepad type in [autorun]
label=any name you were (optional)
save it as AutoRun.inf be sure to use the drop-down menu at Save as type and switch to All Files (*.*)
put it and a icon named logo.ico in the removable media.