Attach webform on each node of specified content type
I had the same question and found answer in drupal community, that was using of Webform Default Fields module.

Here are a brief description about this module :


  Description
  
  With this module you can easily create a lot of nodes with same webform fields. It can be applicable in case of job vacancies with reply form, kind of quality feedback control or whatever your mind suggests you.
  
  Because you can create more than one webform-enabled content types, you respectively can attach different default fields for each of them.