SharePoint Workflow Action & Item Receiver - repost

I have an exe that takes input and output parameter. I need a workflow action to be created for SharePoint that can use the exe. The executable basically takes input document (office type, jpg, etc.) and outputs to PDF. Basically, workflow action should take the current item and ask for target location and convert the list item to pdf. it shouldnt overwrite the existing pdf if a pdf with the same name already in list. I also need to have a ECB menu created "convert to PDF" that can use the same exe and convert the sharepoint item to pdf.