I know I've heard/seen a few people say that the Number 1 ranked team will get to choose which site they play at, which does not appear to be true. Nor are the 1v4 and 2v3 sites already selected.
From the CFP Wesbite:
Pairings for Semifinals.
From the CFP Wesbite:
Pairings for Semifinals.
- The team ranked No. 1 by the selection committee will play team No. 4 in the semifinals. Team No. 2 will meet team No. 3.
- When assigning teams to sites, the committee will place the top two seeds at the most advantageous sites, weighing criteria such as convenience of travel for its fans, home-crowd advantage or disadvantage and general familiarity with the host city and its stadium. Preference will go to the No. 1 seed.