How do I get a node based on id in custom content type? I have a custom content type A that has a field for node id which refers to a different content type B. While creating my view for content type A, I want to identify the id in the field entered by the admin and based on the id find out what node of content type B is being referred to and generate a teaser view for B in the View of A. Does anyone have any insight on how to do this? Its more like providing a list of References with links to an Article where Article and References are both different content types.
This is exactly what the node references field modules do. For example in your Article content type, you would create a new field 'Related to References' as a node reference field and link it to relevant nodes of the References content type. The field stores the title of the referenced node and its NID which makes it a lot more user-friendly interface than using a nid.

If you're using Drupal 7.x, the current recommendation is to use the Entity Reference module which takes over from the Node Reference module in CCK.

If you're using Drupal 6.x., you want to enable the Node Reference field which is part of the CCK module. This still leaves a migration path to 7.x by upgrading to the 'References' field module, and then migrating your reference fields to Entity Reference fields.