Is there any resource recommendations in general for getting past the basics of QGIS and going into the deep dark secrets?
Specifically in relation to expression coding for labeling, queries, etc.
Underdark has composed some nice examples for labeling expressions:
Here are some helpful links for querying:
If you are interested in coding then you can start with this resource:
a nice blog with good QGIS tutorials : http://woostuff.wordpress.com/