Hi MBT,
Your Auctiva store is an entirely different storefron than an eBay store, and can be customized to your liking using the customization options under the "Store" tab within your Auctiva account.
While the Auctiva store window displays a selection of 14 of your active listings at any given time, your Auctiva store, which can be reached by clicking the "View my Other Items for Sale" link on the bottom right of the store window in your listings, displays ALL of your active eBay listings at any given time.
The custom domain you have purchased through Auctiva is managed by Auctiva and can only point to your Auctiva store. If you would like this domain to point to your eBay store, you would have to purchase the domain outright from Auctiva, which would allow you to manage the domain however you choose. If you wish to do so, please contact our customer support department for further information on how this can be done.
If you have any further questions, please don't hesitate to ask!
-Mike