Hello,
1. Yes, this is the default functionality of the theme. When you will select the variation on the product grid then it will only load one image from the gallery related to that color or variation now the other images in the carousel.
2. This is not a bug, and it should not work as he wants. These switches are present ONLY to quickly preview of possible variations images from a single (chosen in theme settings) attribute and are not related to either variable products (which can consist of several attributes simultaneously) or a single product page in general.
Yes, we have two quick shop options for the grid (https://monosnap.com/file/Yn2wlBOJGmnq6ZX7iA4a2i38AiAfGZ), but both are designed for quickly adding products to the cart directly from the shop archive, without visiting the single product page.
Essentially, the grid is separate, and the single product is separate and there are not interconnected
Best Regards.