Hello,
Yes, the component is suitable for such kind of configuration.
1 - You can also add variants from the frontend ; it requires, like in the HikaShop backend to add a characteristic to the product
2 - It's a social plugin related to HikaShop ; it's not from HikaMarket
3 - You have to change the HikaMarket configuration for your default access ; there you can select (or remove) every feature that you want to give to your vendors. The "product / edit / acl" will remove the edition of access level for product and the field won't be displayed anymore to your vendors
4 - Yes, there is Products and Category Search plugin (for your HikaShop related question, might be better to post in the HikaShop section of the forum)
5 - Just like the "product / edit / acl" ; you have an entry for "vendor / edit / users". For sure if your vendors are just associated to one single account, you do not need the multiple-user per vendor feature and you can remove that entry.
6 - By editing the default access, you can remove every fields you don't want anymore. Such as the product options, product related, etc.
Please note that if you remove the characteristics, you won't have the possibility to create variants anymore.
Regards,