Good question ...
Let's hope someone knows those answers.
I used Sdgallery for a long time until I found Auctiva. Then I dropped them but I had to delete each scrolling window from over 1,500 auctions. Then Auctiva was having problems pre-CHRISTMAS and again when they moved their servers so I had to go back to using Sd again.
Now they sold out to InkFrog which I am sure is going to raise the fees so I hope you find this answers as I will most likely drop them again.
I am just using both right now until Auctiva settles down and gets running smoothly for at least a week or when InkFrog takes over for good which is suppose to be June 1st