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 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?