Hi,
2) I see what you means. The HikaShop search in the backend can't look into the VM field..
I don't know if the order number has an importance or not for you ; but you can see to copy the order_vm_id into the order_number if you want to use that id instead.
You can use a mass-action to perform the copy or you can use a query like that :
UPDATE #__hikashop_order SET order_number = order_vm_id WHERE order_vm_id IS NOT NULL AND order_vm_id != '';
But using the query will remove the imported order_number.
Otherwise, you can see to use some overrides (or modify a little the order listing) to add the "order_vm_id" in the search filters.
Regards,