I am building an image-centric catalog website. It catalogs collectible gaming cards numbering 100,000+ pages. There are competitor sites receiving millions of hits each month, so with the possibility of excessive traffic, I need to moderate image bandwidth while also optimizing for image SEO. I'm looking for some tips on doing so.
Here is a simplified example of my current code: I left out the thumbnail-to-full image replacement script for simplicity. Would this affect SEO in any way? Should I be doing anything differently? Note that I don't want to create a page for each image as I'd have to duplicate the card tags and descriptions on each one, diluting PR for the main page. Thanks for any insight!