Open Cart modifications

I have an Open Cart installed, but I want a few modifications. 1. I want each category to be displayed with a thumb / icon before the text. Thumbs must be editable by admin backend. A different icon image for each category. 2. All products need to be showed with an extra image, just below the main image, in the product list. This image also needs to be shown on the product page. Images must be editable by admin backend. A different image for each product. 3. The product page needs to be restyled a little bit. very simple. All modifications must be: - without touching the Open Cart core code - remain responsive