Not possible to uninstall IE, it's integrated into the windows shell pretty doggon good. IIRC it may have been possible in 9x and previous versions, but not in XP.
Sure it is. You insert your CD and select "Remove Windows Components". Whether it actually removes the program I don't know, but it makes it inaccessible and forces programs to launch Firefox instead of IE to open web pages...
Yes, it is very dirty, and bound to get even dirtier with Longhorn, when Microsoft intends to make the browser a seamlessly integrated part of the desktop, rather than a separate program.