Hello,
1) The image from the next variation is displayed when you hover over the product. You can try changing the image of the variation by editing the product.
2) Please provide a relevant screenshot of the specific area with the URL of the website to check it myself and help you out accordingly.
3) To hide the add to cart button try adding the following Custom CSS area under the Global Custom CSS area under Theme Settings >> Custom CSS.
.product-grid-item .woodmart-add-btn {
display: none;
}
Best Regards.