1) Make default category view to arrange products by price from highest to lowest.
2) "Flush" database of old URLs so that the mens category is /mens/ and not /mens-1/. There are a few categories that are like this.
3) Remove "Categories" and list of categories from the sidebar. Since they are available in the top navigation bar, I don't think it is necessary.
4) Option to filter by size available (and in stock). I have attached an idea to illustrate what I mean.
5) Price range slider. I have attached an idea to illustrate what I mean.