I have added feature 1) to the EOS master branch, it is available since EOS 4.8.79 . See Cern Authentication
Assuming you have created the space SHARED with a shared filesystem, one can enable this feature by doing:
eos space config SHARED space.policy.localredirect=1
You can find the description in the documentation “Using EOS/Policies” Space and Application Policies — EOS CITRINE documentation)
I am currently finishing a file adoption feature, where you can sort of grab an arbitrary file in a shared filesystem via a hardlink or symlink into EOS.
Cheers Andreas.