Answers to most of my questions from my experience now having a GrapheneOS phone for under a week:
- No, 3rd party sync through the games cloud sync or accounts will most likely work like W1zardK1ng said.
- Through the Play Store it works perfectly.
- No automatic installs but automatic updates in the Google Play Store works, Neostore has manual updates.
- Haven't tried yet, but W1zardK1ng was probably right.
- Yes, perfectly with no issues. It even still is optimized for the 7's camera.
So far it has been a seamless experience with the only issue being transferring from my old phone, but that's not a big deal. All my apps have worked great with no issues currently. I am probably the least de-googled GrapheneOS user though, as even though I want to leave google, I'm still stuck in some of their ecosystem and I prefer some of their apps over others. This includes their messages, GBoard, and google camera as I have my reasons to prefer them, but I made sure to disable telemetry in settings and also in my Google account settings.