Many questions here, but could you detail where you have issues. So, your requirements are:
1) Convert smart form into PDF. Is there an issue in that?
2) Add the PDF as attachment. Of what? email? workitem (but why)? Do you have an issue with that?
3) Based on a given user decision in a workflow, trigger 1) then 2) Is it really what you mean?
Last thing, I didn't understand why you need a "program exit" (is that the exit you define in a workflow step? Can you give more info?).