How to design Drupal forms without coding a lot?
Drupal has a really nice Webform module so if you want to avoid programming you can install and use it:
https://www.drupal.org/project/webform/releases/6.x-3.23
Check out for i.e. Youtube tutorials about this module. It is well documented.
But if you want to go with codding solution it's up to your codding style and code organization.