-I would switch Agger and Carragher, as Agger is left-footed and Carra is right-footed. You might also wanna consider playing Agger as a BPD (perhaps as stopper, with Carra as cover), as he has perfect attributes for a BPD.
-If you're gonna use Sterling on the left wing (which I do myself), I'd play him as IF.
-I would play Skrtel instead of Carragher.
-Reina is perfectly suited for playing as Sweeper Keeper. But it depends how high you play your defensive line.
-Suarez seems better fit to play as AF rather than CF.
-As for transfers/improvements, I'd go for Wellington Nem if you're in the first transfer window. He's worth almost £20m in my game (february 2016), so you will be able to sell him with a huge profit later on. He's also great as an IF on the right wing. I was also able to sell Johnson to Spurs for £28m after the first season, and Chelsea bought Shelvey for £30m the season after that. I would get rid of Doni, Downing, Cole, Henderson. Use Shelvey, Suso, Coates and Sterling as much as possible, they all develop at a good rate. Other signings you might wanna look into is selling Reina and buying ter Stegen as Reina is not getting any better, and you should be able to sell him for about the same amount that ter Stegen costs.