I bought Podolski as he can play as a winger or striker, and he has been brilliant for me. If you play with a defensive midfielder and a ball winning midfielder, you will definitely need more cover for Kehl. He will get injured a lot as he gets older, and you don't appear to have any cover on the bench. Lars Bender may be a good, cheaper option. Also, Marko Marin has been a quality signing for me.
Piszczek, Owomoyela, Hajnal, Rangelov and Sobiech aren't good enough, so I would try to sell tham all