How to determine where the CCK fields are stored in database?
You want the content_node_field_instance table. As that table defines each "instance" of a field on different content types. For the field configurations (global configs, independent of instance configs) you want the content_node_field table.

Similarly in Drupal 7 there's field_config table for global field configurations, and field_config_instance table for each instance of a field with content types.