I would like to suggest some other features which is :
1. Save Product detail fields to [Order Item] table when customer make an order.
(product detail must be the same as is value as the customer saw when ordering it)
In my experiences, this can be used to prevent mis-communication or even fraud done by a vendor.
Customer may complain if he/she received the ordered product(s) with different condition as it was described when ordering.
When the customer recheck the product detail page, it was changed / updated already by the vendor, which can lead to the problem.
2. In vendor detail page (public store), right now, all categories and manufacture is listed (not just about the vendor's products only).
Can we just only show list of categories & manufacture which related only to the vendor's product?
This feature really helping when a customer wants to filter vendor's products.
3. At the admin area, menu system > message queue, Adding mark as read button (new field for message status) will be helpful for admin to manage it.