Sharing Photo Album with Family and Tagging

Greetings.

My husband I and both have separate Apple ID's but want to both look at the same photos in Photos. We can do this on Dropbox easily... we just use the same account. When he adds a photo to a folder it syncs across all of our devices instantly. I'd like to do the same in Photos. "Sharing" my photos with him seems like a silly term since I want him to have full access to everything and I've heard you can only share one folder? I'm also interested in tagging. For instance. I tag the photo "Florida" and when either of us types in "Florida" all those photos pop up. We'd like to do this on any device.

So my question is, how do we share all our photos which are located in multiple albums and do this across all of our devices? Also, can we tag them with keywords and can we both use this feature to find the photos instantly? We, of course, want to keep our own Apple ID's. Dropbox does everything but the tagging. Should we stick with that? Thanks!