When you set up these sub-categories you have the option of including an image...Go back and add imnages to each as see if this makes it more like what you want
Secondly, how can I add a drop down box to select a size, color, or style of an item in my store
This is by adding attributes to your products
First a name like "size" and then add values to these names like small, medium...Lastly associate or add these attributes to the product

There are aids in the FAQ's and the wiki for attributes for more detail