How to fix blurry product photos on Dawn theme?

Hi, so I only have two products as of right now, so when I set the columns for my products on my main landing page to 2, it blows the pictures up and causes them to be blurry. When I set the columns to 3 they are not centered, but are clear.

I am wondering how to fix this in one of two ways:

  1. What dimensions/resolution would be best for my pictures so that when the column number is set to 2, they maintain their clean and clear form?

  2. If I set the column number to 3, how can I center my two products (move them to the left), so that they are directly under my main picture?

1 is the preferred method, if possible.

my store: shopgyh.com

Password: CommunityForum