thanks for choosing my plugin. Following the answers to your questions:
1) Buy, build or choose a template similar to mine ;) Then use a floating layout, which is defaultly provided. (I use exactly the same CSS as I provided in the plugin - appart from the theme specific Fonts aso)
2) Currently not but you can reduce the quantity of articles by using the category option. (Build a category and tell the plugin to use the category 'shop_category="CATEGORY_ID"')
3) Sure, currently the background depends on the layer displaying the articles, but you can also choose a different one. Please have a look at the plugins' CSS.
Hope this helps.