Possible to have Best Sellers / New Prod Pages?

Hi,

Sure. You can go in the Joomla menu manager and create a new menu item of the type "HikaShop products listing". Then, in the HikaShop options of your menu items, you'll find plenty of settings to configure how you want to display the products.
If for example you set the "ordering column" setting to "product_sales" and the "ordering direction" setting to "descending", you'll get the best sellers at the top of the listing and the less sold items at the end.
It's the same with the "product_created" column for the new products display.

Hi,

You want to set the "sub elements filter" setting to "all sub elements" so that it takes into account all the products of the sub categories of your main category. Otherwise, with "direct sub elements", it will only take into account the products directly linked to that category.
Also, you want to turn off the "recently viewed" setting. Otherwise, it will only take into account products for which you previously displayed the product details page.