There is no gap like an air gap. That said, unless you have painted a target on your back somehow, a private user should be safe enough being connected.
Two different ways to reduce the object distance:
https://photo.stackexchange.com/questions/60546/what-type-of-lens-can-i-add-to-my-webcam-for-closeups-5-20cm-away
https://community.ultimaker.com/topic/30707-alternative-for-microscope-webcam-close-up-lens/
Allway Sync is great and it won't keep bugging you to purchase the Pro version or to do anything else! It does exactly what you tell it.
https://allwaysync.com/
To use the external hard drive to store or move files, just format it (NTFS). All that pesky stuff should disappear. I do recommend using a cloud drive, as others have above. I prefer Pcloud because you can set it up however you want. IF you have MS Office 365, you already have OneDrive and you...
I have the same problem with an intermittent request for log in on startup. If you click on the power icon in the lower right corner of the log in screen it will give you two options, shut down or restart. I just go there and restart and the desktop restarts without the log in request.