Hello,
To display products under the vendor product page, you have to display a product listing module like you can do for listing products with a category listing menu.
First, you have to create an HikaShop module, for your product listing. The important option is Synchronize with currently displayed item when possible.
If you want to have "vendors' categories"
www.hikashop.com/support/documentation/1...nfig_market_category
1 - You can copy categories in the HikaShop backend but I don't have the feeling that it's the meaning of your question.
2 - Yes you can use a mass-action to set the "product_vendor_id" to all products targeted by your filters.
If you want to duplicate products when a new vendor is created, there is a plugin in HikaMarket for that.
But that plugin do not support the duplication of categories ; it duplicates only the products of one category into the new vendor root category.
Regards,