Is there a place to set the article columns to separate in pixels or can I actually create a fine line between article columns? Maybe a place in CSS to do this? It would seem that there would be some system-wide K2 function for this option. My articles stand shoulder to shoulder on my home page and frankly it looks bad.

This is a template issue, without a link it is really hard to assist you.
By default there is padding but the developer must have stripped it.

If you are using a commercial/free template by another developer, you need to address this issue to the developer.