The first move a GM must make is to keep the players you have at home. Resign Reggie Wayne and Mathis so they are available to help bolster the offensive and defensive units. Wayne has several good years left in him and Mathis compliments Freeney on the defense. Keeping those two together will help stabilize the defensive unit for the coming year. With some pressure on the oppents quarterback and some beef up fornt to stop the run the defense can be salvaged and become a force to help take the pressure from the offensive unit.
As for the quaterback position I would do the following. There needs to be a serious converstaion with Andrew Luck and Peyton Manning. You have arguably the best quarterback in the game and the posibbility of drafting the next great quarterback coming into the game. Luck seems to be in the same mold as Manning so the fit seems perfect. However if there is not some understanding as to how this will all work out you end up with a situation that will affect the entire team. I would have the conversation with the two with this in mind. I would draft Andrew Luck and have Manning become his mentor. They would travel together, eat together, room together and Manning would pass on his wisdom and work ethic in this game.
The plan is to have Manning be the starter for the next two years, about the time I feel Manning has left, and then have Peyton transition into the quarterbacks coach to continue his relationship with Luck as he takes over the team. This would lend stability to the position for the years to come and allow the team to concentrate on other positions that need help such as running back, defensive backs and the offensive line. Luck would get playing time during the season when the games are out of hand or there is no real reason to start Manning, such as the end of the year when we need to rest starters for the play-off run. As Luck matures in the game then the trasnistion from Manning to Luck could begin.
The only other situation that might need addressing is the head coaching position. I would keep Caldwell throughout his contract and evaluate as you move along. There must be communication but not meddling from the GM. If the two parties cannot agree on something then a serious look must be taken at the philosophy of the head coach and the GM to make certain they are aligned with the plans the team has for the future.