Thanks for sharing the sample and more details.
1. At the moment, you can use replace text feature to update text in a PDF; formatting of old text will be applied to new text in this case. If you want to add new text, this feature is not supported at the moment but a new feature request has been logged into our issue tracking system as SAASPDF-76.
2. You can extract images and use image resource to replace images in the PDFs but if you want to add a new image without replacing any existing image, then this feature is not supported at the moment but a new issue to support this feature has been logged into our issue tracking system as SAASPDF-77.
3. Currently, you can extract CAD drawings as images if those are added as attachments but in your case CAD drawings are not added as attachments so this feature is not supported. A new issue to support this feature has been logged into our issue tracking system as SAASPDF-78.
We will keep you updated on these issues in this thread and share an ETA once our developers analyze these features.
Support Developer, Saaspose