Is there a maximum number of images per product? You could do a separate column for each picture if there is a maximum number. If you need to support unlimited images then you would have to use a relational table for the images.
I'd do a path like: images/[product_id]/[imagename] and just use the name the client uploads.
If you upload the full size image (I would not resize on upload unless it is over the maximum size you want to support), then you can use Image Resizer to show it as a thumbnail.