- Yes, all the observations feed into the same database and are viewable by anyone.
- There is some technical discussion here: https://forum.inaturalist.org/t/if-logged-in-on-a-network-site-log-the-user-in-on-all-other-network-sites/52331
- Also discussed in the above topic, though see https://forum.inaturalist.org/t/stay-within-your-inat-network-affiliation-domain-when-clicking-links-to-other-inat-network-sites/6898 for a couple workarounds (using Requestly or Tampermonkey)
For more info on iNat network sites, also see https://help.inaturalist.org/en/support/solutions/articles/151000171181-what-s-the-inaturalist-network-which-site-should-i-affiliate-with-