Create nodes in a installation profile How can I create nodes in a installation profile? Can this be done in the .info file, or does it have to be done in the .install file?
When a profile needs to create something to make it accessible once the profile is installed (e.g. blocks, content types, fields), it does it in its hook_install() implementation. For example, the standard profile creates content types, fields, and input formats in its standard_install(); it also enables some of the standard blocks, and it set the Seven theme as administrative theme.

Drupal doesn't use any directives in the .info file to automatically create nodes, but a profile could implement code to parse extra directives in a .info file, for example in hook_modules_installed().

I would rather go with implementing hook_install(). I may consider using directives in the .info file if there is a module handling them and I am writing more than three profiles for which being able to change the nodes added from the profile is much important. I understand that avoiding to keep changing the code make less probable to introduce errors; since I know the code to use to create nodes, and the task is relatively simple, using directives in the .info file doesn't simplify much the code I would write for a profile.
I would take more in consideration a module that would back-port to Drupal 7 the code that in Drupal 8 handles the configuration files used to create content types, and fields for those content types, using YAML files. For example, this is the core/modules/forum/config/optional/node.type.forum.yml file that in Drupal 8.3 allows the Forum module to create its content type. 

langcode: en
status: true
dependencies:
  enforced:
    module:
      - forum
name: 'Forum topic'
type: forum
description: 'A &lt;em&gt;forum topic&lt;/em&gt; starts a new discussion thread within a forum.'
help: ''
new_revision: false
preview_mode: 1
display_submitted: true