can i add a fillable pdf to my site that a viewer can open, download, fill out, save and email the completed pdf to themselves?
1 The pdf can be uploaded to the site like all other static files and users will be able to download.
2. Filling PDFs is done through dedicated applications like Adobe Acrobat Reader and not DUDA.
See https://support.duda.co/hc/en-us/articles/4410652602135-Upload-a-File on how to upload files.