Fix small problems on oscommerce site

Hi, there is a few problems that need to be fixed on my oscommerce website: 1.) The "sort by" links on the categories are going to an invalid URL. 2.) I have a product filter on the left hand side of the categories. However, it is only showing up on top-level categories. 3.)The breadcrumb is showing incorrect urls on sub category pages. For example. A third level sub category would show: "catalog/3rdlevelcategory" instead of "catalog/1stlevel/2ndlevel/3rdlevelcategory. This will cause google to think there is duplicate content. 4.) I need a field removing on the checkout. I have tried removing this before, but it still comes up with an error stating i haven't filled in that field. Some addons: 1.) I need an xml google sitemap.