I can't answer all of your questions, but maybe I can help on one or two...
I am not 100% certain about this, but I don't think you can delete "imported" listings--I tried to delete several of those before and they kept coming back too.....
When I look at my Closed Listings, it tells me on the right column if I have relisted it and the ebay item#. It doesn't say anything about credits or how many times I've relisted it though. Also, when I sell fixed priced items and not all of the quanties sold, it says that too in parenthesis so when I do relist, I can adjust the quantity accordingly. Does anyone know if you use the Inventory Wizard, will it make those calculations for you? I haven't used that feature yet, so I can't speak for it's functionality.
I don't think Auctiva has the capability to differentiate whether or not an item is eligible for a relist credit--they have no idea if a dispute was filed or if there's another reason why an item that was supposed to be sold wasn't and is being relisted (like when you have a NPB.) And now that ebay is eliminating the relist credit for Fixed Price listings, it makes it even more confusing.
I wish the Saved Listings page would have info about the item's status (i.e. if it successfully sold the first time around or ?)and on the Closed Listings page why isn't the final sale price noted?
Once you get the hang of Auctiva it is a great listing tool. And who doesn't like to save $$ on templates, supersized images, etc....?