hook_views_pre_render -> how to access variables
Install the Devel module if you haven't already and use dpm($view); to see the structure of the view, then you can drill down to the part of the variable that you wish to inspect.

The devel module will print the result of your dpm() in the message area as long as there are no syntax errors in your module crashing the site.

I have found drush cc all (Linux command line tool) to be useful in finding syntax errors though I suspect there is a better way.