The Big 12 actually does have a clause in their contract that limits expansion. If they expand to 12 teams, then they only get enough of an increase to keep the payout at the current level. They have to add more teams to get additional money. To your other point, the Big 12 didn't expand precisely because they were told they wouldn't get more money for the teams available. They consulted the networks before they expanded, during the investigation phase.
Your questions have already been answered. The formal proposal calls for the first round to be played on campus. The second round will be played on the NY6 bowl on new year's. The semi finals will be played the following week in the remaining NY6 bowls. The title game the following week.
The title game is already played after the NFL playoffs start.
College teams already have to deal with sharing stadiums with NFL teams. It's not hard to do.
When is the last time the networks have turned down playoff expansion for a league? The NFL, NBA, MLB, NHL, and CFP have all expended their playoffs, and weren't turned down.
There is just way too much to the contrary evidence to make a credible argument that TV will turn down expanded playoffs.