Thanks mr_planescapist for your productive and helpful comment for those of us who do use Stadia and bought the game for the same price as you did. You're awesome.
AnnaKin89,
We've experienced all of the same issues. It helps with the camera falling through the ground and when the camera starts going crazy, at least in combat, to use L1 or R1 and it will pop your view back to something more stable.
We're also experiencing weird issues with controller via Chromecast losing hotbar control, but it's not happened with controller via USB to computer.
It seems they did fix the "waiting on other characters" leaving camp problem we were having previously.