How to get a dropdown list with content of other content type
You need to use Entity Reference module..

Project page says


  Provides a field type that can reference arbitrary entities:
  
  A generic entity reference field
  
  Four widgets:
  
  Two implemented on top of the Options module (Select and
  Radios/Checkboxes),
  
  Two autocomplete widgets (one with one text field per entry, one
  tag-style with comma- separated entries in the same text field)
  
  Two formatters:
  
  A "Label" formatter, with optional link that displays the label of the
  referenced entity (the node title, the user name, etc.)
  
  A "Rendered entity" formatter, that renders the references entity
  using a configurable view mode
  
  Integration with Views (for both forward and backward references)
  
  Integration with Entity Metadata (and as a consequence with Search API
  and the like)
  
  Integration with Devel generate
  
  Integration with Feeds and Migrate (>= 2.3) for painless data import