passing form fields to next page in drupal_goto()

The second argument of drupal_goto() is the query string.
http://api.drupal.org/api/drupal/includes--common.inc/function/drupal_go...

But when you are developing a module,its better to use hooks like hook_form,hook_insert.

This is not a critical issue, nor it's in the relevant module issue queue. I suggest you take a look at the following modules:

• Multipage form controller
• Multistep
• Webform
• Chaos tool suite

Just a note, drupal_goto() will stop the flow of whatever is it that you are doing and is not the recommended way of redirecting after a form submit. Try $form_state['redirect'] in your submit hook.