A way to generate line charts where each dataset comes from a view with specific arguments
'I' can answer that very last part of your question about charts. The views integration of the charts module is a solution for that. Here is an intro about it from the charts community pages: 


  Anybody familiar with the views UI can use the charts module to create
  charts without coding PHP snippets, as one typically does when using
  the Charts API.
  
  So site building knowledge is sufficient to create charts using Views,
  you don't have to be like an experienced Drupal developer (who
  probably would rather want to use the Charts API instead).


To be complete: I'm the new co-maintainer of the charts module ... Working on transforming the latest (pretty old and stable) RC1 release of it in an official release of it.