**Really need help with shop and product pages**

I am trying to change the design of the shop and product pages and I am running into a few issues.

Can I get rid of the dropdowns of “sorting by popularity” and “show 4 per page” so I can just display the products? How do I stretch the header to increase the height?

I have a product that comes in different sizes, and I was wondering how to add this to the product page without making separate products. How do I add sizing functionality?

The price that is displayed on the product pages is white and extremely hard to see. How can I change this?

The image on the product page has a diagonal white stripe in the top left corner and I was wondering how to get rid of this.

Is there anyway to make it so when you click an image in the gallery, the featured image changes?

On the shop page, if a product is on sale, the text is overlapped. Is there anyway to make the text centered and not left justified?

The biggest issue is that the footer is still displaying even when I turn the footer off, and it says “Experience something completely different. The most powerful theme ever.”

I think most of these issues stem from my inability to find the necessary classes and tags to customize in CSS, and I was wondering if there is documentation or do I have to manually sift through the entire CSS file to find them?

This site is going live next month so I would really appreciate any help.
Thanks.