Need help: How to crop in Aperture?

How do I crop a photo in Aperture so it becomes a new and separate image without losing image quality and while keeping the original.  There are two issues I keep experiencing with this and I'm sure it's user error:

1)  When I crop a photo and go to move that photo to a different folder it moves the original photo as well. How do I make the cropped photo a separate photo with the ability to transfer to other folders while leaving the original photo in the original folder?

2)  When I upload the cropped photo to Costco it goes from a 5MB file to a 587KB file in Costco, which is too small for larger prints.  What am I doing wrong?

Thanks.