There are no swap fees for NFL Tournament format contests. There is also no limit to how many you can process, as long as you adhere to the below rule.
All swaps must be completed prior to game time for the players you are swapping in order for their points to count.
e.g. You can swap a player on your team who plays at 1 pm EST for a player who plays at 4 pm EST, as long as the swap is completed prior to 1 pm EST.
The same goes for a player who plays at 4 pm EST. You can swap them for a player whose game starts at 4:15 pm EST, as long as you complete the swap prior to 4 pm EST.
If you swap in a player after their game has started, you will not accumulate points for the player being added to your team.
*Players who have been dropped from a lineup cannot be picked up again during the same contest.