if you want to have the right hand content context oriented like here on ez.no then you should alter your content model. Here on ez.no we use a class called information page which has the following attributes:
* Title
* Body * Right info
The right info is simply an XML text field which is displayed to the right, if enabled. We have a checkbox in the class to enable/disable this feature.
regarding cache: we have this right information in the view (article/folder) template directly. Then the cache is handled like normal objects.
If you place this in the pagelayout then you should cache it with cache-block. But remember to make the node ID part of the cache key. Cache blocks are purged on publishing by default.