Add webform to content type
You can do it by node reference. Add those kind of field to your content type. You can always set default value for automatic add webform to node, but it doesn't add you form automatically to node edit form.

I test it by using node reference and views, but it doesn't display a webform on node edit page (in the same form).

You can try to use hook_from_alter, which means to add programatically fields from reference webform. IMO is the only solution or maybe there are some modules for this, but I didn't look for them.

You need add your submit function to this form too, because you need to filter and save webform fields programatically too. Check WebForm API for this. A lot of work, maybe you should think about better solution without programming and using webform at all?