Hi,
About the order number, you will have to do an extra "step" during the import.
The "order_number" in the virtuemart table is the "order_number" you see in the HikaShop table afterwards.
I don't know why but Virtuemart does not display you the "order_number" stored in the database but display the "order_id" (with some formatting, but the value is the order_id).
The normal way in HikaShop and Virtuemart, is to display the value of the "order_number" as the order number.
If you want to display the same value than virtuemart display you, you will have to modify HikaShop like you modified Virtuemart or simply import the "order_number" you want into the HikaShop table.
UPDATE `#__hikashop_order` SET order_number = LPAD(order_vm_id, 8, '0');
For the problem in the import of order/user, the patch is already commit into HikaShop and will be include in the next package (I think in a hot fix for HikaShop 2.3.0).
Regards,