Here's a suggestion for the cart layout.
Instead of having the update and delete buttons right next to each other to the left of each item in the cart, I think it would be better to have the update button to the left of the item (near the quantity field) and the delete button to the right (all by itself).
This would leave the update button where it is most needed and move the delete button far away to avoid accidental clicks of delete instead of update.
This would also allow for larger buttons with pictures (I'm imagining a big red X for the delete button, but have not figured out a good picture for the update button).
Thanks,
Richard