How to show fields in different regions?
As with anything in Drupal there are many ways of doing this. Display suite and Panels (as mentioned by Serpiente above) are great. However, if you are not already using them for your project, they are indeed overkill to get what you need.

You can use the CCK Blocks or Field as Block module. These essentially turn any field (you set) into a block to be placed in another region.

You can also use the Views module to create a block with a contextual filter based on the nid in the url and display whatever fields you choose.