Hi,
1 - Please be sure that you are creating a product with a vendor and not with your main vendor.
The usage of "%d" is to place the vendor in a very particular place in the string, like
Otherwise it will use the prefix and put the vendor ID (and an underscore) just after it.
If the product code already start with the generated prefix ; HikaMarket won't use it (because the prefix already been set before).
2 - Please be sure that your vendors right have the ACL "product / edit / fields".
Then in the HikaShop backend, edit the fields you want to make it visible for your vendors ; you'll find specific settings for HikaMarket pages.
3 - The specification tab ? I'm not sure that you're talking about the HikaMarket part.
Can you please provide further details ? A screenshot maybe ?
4 - Like point 3 ; I don't see what you're talking about exactly.
5 - JCE is initialized the same if you create a new product or edit one.
In another post you gave a test access and I was unable to see the difference in the editor between "creation" and "edition". In both cases the editor did not provide any tool (empty toolbar) but was initialized.
Like I wrote in the another post, it comes from the JCE configuration ; please see that directly with the JCE support team because it is currently outside our level of expertise.
Regards,