Hello,
1. If you want to create megamenu go Appearance > Menus > Create Shop item(1-st menu level) with subitems where 2-d level will be column title, 3-d – column content. Save menu to see additional theme options for menu after that. Choose Design > Megamenu and select number of columns you need.
You may use Product Categories in menu http://www.flyingpixel.co.uk/flying-pixel-help/wordpress-help/woocommerce/adding-a-woocommerce-product-category-to-a-menu.html
2. Go to Pages > edit Home page and edit Products VC element on every tab. Select product type and sorting order according to your needs http://prntscr.com/bsg0ja
3. You can create page with content you need (coming soon etc.) and add into menu custom link with title Portfolio for example but link add to this custom page. Once Real Portfolio page will be created you just replace the link in menu.
4. Unfortunately, our Product Categories VC element does not display empty categories. But you may use Woo Product Categories element to add all the categories you have http://prntscr.com/bsg2dc
Regards















