The Celtics have 9 players under contract right now with a total payroll of 71,369,509. That alone is more than likely going to be over the salary cap and very close to luxury tax level. They also have 6 free agents: Tony Allen, James Posey, Sam Cassell, PJ Brown, Scot Pollard, and Eddie House. They have the MLE (5.8 million), the LLE(1.8 million) and veteran minimum salaries to work with in signing free agents.
The first and more important priority has to be to do whatever it takes to sign James Posey. Posey is key to this team if they want to repeat. He is a player who will do whatever it takes to win. He is a lock down defender, capable of shutting down the opposing team's player. He rebounds, dives for loose balls, takes charges, hits the big shot in crunch time, and gives hugs to the starters before the game. Most importantly, he brings leadership and a championship mindset to the team. You just can't replace a guy like that.
The Celtics biggest rivals: the Lakers, Pistons, and Cavaliers are all interested in luring Posey away from the Celtics. There is a very good reason for this. One of the problems that each team had with the Celtics was that none of them had anyone who could stop Paul Pierce. If they get James Posey, they have that player who is capable of stopping Pierce, along with every other star player in the league whether they are guards or forwards. They also had problems with players fading in crunch time. With Posey on their team, they have a player who consistently came up big in crunch time. Danny needs to do whatever it takes to keep James Posey in green.
PJ Brown is planning to retire and Scot Pollard shouldn't be offered a contract. He isn't what this team needs. The Celtics need a center to back up Perk. Chris Andersen is in Boston talking to Danny and he would be a great back up center. He brings energy off the bench, is strong and a good defender. He wants to be a Celtic and Danny needs to sign him. I think he would take the veteran's minimum to play here since it would be a great situation for him.
Sam Cassell should retire and join the Celtics coaching staff. He didn't work out as hoped last season and so if he wants to play another season, hopefully it will be elsewhere. The starting point guard spot is solidly filled with Rajon Rondo, but Danny needs to address the back up. Gabe Pruitt is looking strong in the Celtics' mini camp and I think he will be able to fill the back up point guard spot. For insurance, the Celtics also should re-sign Eddie House. House can back up both guard spots and if not needed at the point, he is a great shooter and could fill in for Ray at the 2. Also, he also is fully indoctrinated into ubuntu. He never complained when his minutes were severely cut in the playoffs and when he was called on, he came up big.
Finally, with the 3 spots left, they can bring back Tony Allen for a veteran's minimum make good contract and keep Giddens and Walker with the team and give them a shot to prove themselves in practice and if they aren't getting enough playing time, they can go to the D-League to get some experience there. To me, keeping the same team together as much as possible would be key to winning again.