iclould photos questions

Hi all,

I'd like to do two things:

1. share all my photos across all my devices, and have them sync automatically through iCloud, so that I can see any photo on any device in its photos app, regardless of whether I took it on my phone, or imported it from an SD card into my Mac mini.
2. create one or more shared folders that I can share with other apple users (my wife primarily) and have the same thing happen in those folders: any photo added to these folders, from any device, is viewable on any other device on either apple account.

I believe this is possible, but I'm having trouble setting it up properly. Is there a support article that describes how to do this?

I have icloud enabled in both the photos app on my phone, as well as the photos app on my mac mini, and I've attempted to create shared folders on the mac mini, but they do not appear anywhere else. (the mac mini photos location is on an external drive, could this be the problem?)

Thanks for any help with this!