A family of Microsoft products that enable users to capture, organize, and reuse notes electronically.
Question
#1
Attached files are also called embedded files. They are indeed physically included in a OneNote section and so transported with it. You can open them or extract them. They are independent copies of the originals or source files.
#2
Yes, you lose information
#3
Links are links as you know them from your browser or Explorer.
In OneNote for Windows 10 you can use links to files on OneDrive, no links to the Windows file system (OneNote 2016 allows both)
#4
You cannot embed a folder's content. You can add a share link to a folder on OneDrive, opens in the browser showing your files in it.
#5
Naturally it affects performance. So I wouldn't recommend using attached files. Only OneNote 2016 has an (automatic) local backup and allows local notebooks. Both OneNotes allow temporarily working offline by design.
Main question
Good path 😄
Bernd