If you already have characteristics in a product and you try to add others to it, the system won't automatically generate the variants. You need to go in the "manage variants" button, remove all the variants. Then, remove all the characteristics of the product and save the product and add them back. That will recreate all the variants automatically.
You need to unpublish your module and add it in the option "modules under the product page" of the display tab of the config so that it displays only there.