Programmatically customise fields in node views
I want to share the solution I found, in order to help future readers.

In Drupal 7 the concept of "formatter" helpt to control the output of a field. For example this tutorial allow you to programmatically define a custom formatter for a given field.

Then by UI site admins (by admin/structure/types/manage/&lt;nodetype-name&gt;/display) are able to chose that formatter (or others) for any specific field.

If you want to declare a default formatter for a field, the best way seems to be while the install phase of the module.
In that moment (At least in my case and in all tutorial I found on the Internet) you use a field_create_instance method to add a specific instance of a given field. According to the official documentation, you can also add the display options that exactly allow you to define the formatter to be used for a specific display (or the formatters if want to declare for more than one display).