sigh ... not this sugar honey ice tea again ..
1. Games with 75 or above are considered 'favorably' reviewed on MC, i-e green check, i-e good, which is the wide majority of the games based on the picture.
2. For any games leaving the service, more get added as well, it's not a service which is counting down to 0 games. That's how subscriptions work.
3. MS tells you well in advance when games are leaving, sometimes a month or more. You find out what's leaving in the monthly announcements, there's a leaving soon section on the game pass website, and there's a leaving soon section on the game pass app on the console.