Hi,
Well, the problem "the website will be placed in the Frame View tab as an iFrame" you're talking in your first message should not happen. I suppose it's an issue with some javascript conflict, or SEF configuration which leads to that. But without checking directly on the problem on your website, I can't provide a solution for that.
Now to have tabs on the product page you can do so by changing the "layout on product page" setting of the HikaShop configuration to "tabular". The HikaShop comment system will automatically be added as two tabs there.
If you want to use another comment system, you can use JComments or JomComment or Komento. When you have either one installed on your website, you'll have an extra setting "Enable comments on products" in the HikaShop configuration where you'll be able to select it and then it will be added automatically at the bottom of the product page. Now if you want it to be added inside a tab of the tabulation system of the product page, it's not impossible, but it would require some development by a developer.