There is an option to "permanentely delete" images if you don't want to wait the full 7 days.
On the bottom of the Manage Images page, there is a button that says "View Deleted Images". Click this button and you will have options to:
1. Restore an image if you did not mean to deleted it.
2. Permanently delete your images.
Watermarking is a planned feature for Auctiva, coming out with our scheduled release in Q1 of 2007.
-Kevin