1) Do you want to edit the product category page? You can’t do this using VC. Product category inherits the shop page layout that you can adjust via Theme Options > E-Commerce > Shop and Product Page items.
Also, you can add the category description in Products > Categories > edit the category.
2) If you want to have home page with header overlap but don’t need this for all the other pages, products then disable this option in Theme Options but enable for the page only http://prntscr.com/ihwz0j