I have a question, I think I already know the answer, which would be no. But I am just looking for an official confirmation from the experts :)
If you have an IE conditional statement for IE6 to include an external style sheet for this browser alone, is this included on the page weight of the page when using any other browser or any other version of IE?
Every other browser should see the "IE conditional" as an ordinary comment in this respect. It is a 'conditional comment' after all. The contents of that comment should not be processed in any way by other browsers if you are targeting just IE6. So, I would agree, "no".