3. 10 wins or more should qualify for an automatic berth
The top 12 teams in the 2023 playoff rankings each had 10 wins or more and that was not including a non-power group of five school. That should be a prerequisite for qualifying. In Michigan's case they look like the current favorite in 9 of their 12 games in 2024, meaning they'll have to knock off another win to feel safe about making the playoff.
A home playoff game in the winter is doable and would be a disaster for an SEC team or a school from the west coast. That's where Michigan's advantage of playing in that bitter cold weather and having a potent run game that they could potentially have would be on their side. Plus there could be a lot of rematches which ruins the sacredness of the game in my opinion, but that won't kill the sport by any means.
Going 9-3 is no guarantee that one will make the playoff and is almost a certainty that you'll probably miss out on unless a lot of losses happen within the top 12. There are no rules, but finishing in the top two of the expanded Power-4 conferences means they'll be automatically entered into the equation, while about five or so other teams could be politicking for one of the four spots remaining.