1) not possible, on listings only
2) categories in your Auctiva storefront are not as flexible as they are in an ebay store, you basically set up a set of search words to seek out like words in your listing titles.
So to search for Size 10 you would need '10' to be in the title of all size ten items and then set the search to look for '10' and label the search as yoou wish e.g. 'Size 10'. of course if the 10 represents something else in another type of item than ambiguity is a problem.
I have not found a satisfactory solution to this sort of ambiguity myself.
With the ebay store you can specify a previously defined ebay shop category for each item at the time of creating a listing. Unfortunately the Auctiva store only implements seller defined searches of the item titles, not the eBay store category. Quite different and rather less useful.
