Hi Snout - excuse me for answering your question to Choo. On eBay in the US, you can specify your listing as being for a 'Digital Download product', such as an e-Book, or a software application - anything the buyer can take delivery of electronically basically. I can't remember exactly how you set it up, but I think you then have the ability to attach the product to the Buyers payment confirmation - that is, they pay immediately, and then get the product, or at least a link to it, by return, all automatically. A great time saver for those selling this sort of product. Currently, we cannot use that on eBay in the UK, and also Auctiva does not yet have the function built into their listing service.
What you may be able to do, but I'm guessing here, is to list normally through Auctiva, and then go to eBay and revise your listing and specify it as a DD product - I don't know if that would be possible, someone else may come along and give more info later.
Regarding the SG - you can specify where it goes via your Store tab, up the top.