Is there a way that I can open and link the .pdf in my notes to an adobe app so that any changes I make to the .pdf in adobe will be saved to the .pdf in my task notes?
Unfortunaetly no. The file upload is not a sync service. Once it's uploaded you need to download it to make changes, or upload a new version. Of course we hope to offer more options in the future, maybe full GDrive support.