Hi,
1 - If the vendor can edit his sub order, the parent order will be automatically update when all sub order will have the same status.
So depending how your store is configured, as long as the customer order just have products from one single vendor, there will be just one sub order which mean that when the vendor will edit his sub order, the main order will follow.
2 - You can customize the HikaMarket vendor order status notification.
But if you put a link to the parent order, I'm afraid that link won't work for the vendors. They can just access to their content so they can't access to the store main order (via HikaMarket) or to the customer order (via HikaShop).
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.