Hi,
You don't need to set the "Minimum quantity per order" if it's 1. Nothing and 1 is the same.
For the volume unit, you can change the default value by changing the order of the units in the configuration of HikaShop.
For the quantity and max, you will have to set them.
If you have the business edition, you can duplicate your existing products by using the "copy" button on the products listing instead of the "new" one.
Otherwise, you can change the qty and max qty values of all your products at once by running a query via phpmyadmin:
UPDATE jos_hikashop_product SET product_quantity = 1, product_max_per_order=1 WHERE 1;