You're really over-thinking this
Just use Auctiva's listing page, add all the pics you want and post to ebay now, or save to do it later. (Scheduling is also free) The only pic you'll pay for is the gallery pic (if you use one) - all Ebay fees still apply but you can have as many additional pics as you want for free, up to 23. There's no need to 'link' anything, not sure what you mean by that.