Need some help with Wix Stores

I am helping out Grace with implementing a wall paper calculator in Wix Stores. I had a quick look at it, and I would like to know if someone has an answer to the following questions:
a) it looks like the Product Page is a monolithic entity, which does not allow adding Wix Code elements, like a collapsed box that, when expanding, pushes all other elements on that same page down. Is this true?
b) I CAN add an image next to the quantity box. But I would like to know is this space is unoccupied (like there are no messages or anything displayed here, see image below in red, where I would like to put the image to trigger the calculator in a LightBox)


c) we would like the result of the calculation returned to this Product Page and set the value of the Quantity box. I see no property to do so. Is there?

Thanks for helping me out helping somebody else out.

Hey
If I would be you I would create Dynamic Pages from the Products Collection so you get freedom in designing and coding the product page. That way you are not hindered from using any element you want. Then you can add your own quantity box and add that number into it as you wish.

You can modify the built in product page in so many ways and you can’t modify contents of the quantity box from code as far as I know.

Thanks, Andreas, that´s what I was afraid of.