Hi,
You won't be able to have a characteristic dropdown on the products listing. That's not handled.
The product quantity dropdown is possible. Just configure the products listing to display the quantity field and the add to cart button, and configure the quantity field to be displayed as a dropdown in the HikaShop configuration and that will do it.
For the other dropdown, you can't do it with a characteristic, but you can do it with a custom item field (that you can configure via the menu Display>custom fields). However, in that case, the price of the product won't change based on what you select in the custom field.
Displaying the characteristic dropdown on the listing would be complex, even for a developer.