Styling issues with marketpress

I have some styling issues and questions. I’ve looked up similar posts, but not of it have worked.

1) On the product page, the thumbnail picture is supposed to be 150 x 150, but it’s making the image small and scaling it up and the picture is coming out blurry. I’ve already tried what this thread said https://premium.wpmudev.org/forums/topic/single-product-page-with-cropped-image and it didn’t work.

2) My product variant is showing the default picture, and not updating when I select a different variant.

3) Can I move and/or style the The category and Order by dropdown menus?

4) On the store main page, I have a grid listing of my products, can I alter the product image heights and/or get more than four products in a row?