Excluding Grealish who's under 21, the first team squad of
Guzan, Bunn, Steer (3)
Cissokho, Richardson, Bennett, Amavi (4)
Okore, Senderos, Baker, Clark (4)
Richards, Hutton, Bacuna (3)
N'Zogbia, Gil, Cole, Sinclair (4)
Gueye, Sanchez, Westwood, Gardner (4)
Kozak, Agbonlahor, Ayew (3)
has 25 players. So if you want to add Angel Crespo, a new CB, Cambiasso, Praet, and Adebayor in there, you have to exclude five of the current squad. I struggle to see us getting rid of five of them (think we'll see Steer, Cissokho, and Baker leave), so I think we'll might only make 2 or 3 more signings.
Edit: can't add.