Former MK Dons midfielder Keith Andrews is to take up a full-time coaching role with the club this season.
Midfielder Gary Deegan has signed a new one-year deal at Southend.
Fiorentina have completed the permanent signing of Cuadrado, buying the remaing half of the player from Udinese.
Despite the Florence club sealing the full rights to the player, he has been strongly linked with the likes of Roma, Arsenal and Barcelona.
But Della Valle insists that he will be doing all he can to keep the 26-year-old out of the clutches of a rival.
"I've always promised to do the best to keep him in Florence and it's my first aim. It's really difficult, but I'll do what is possible," he said.
"We haven't spoken with anyone and we have not asked anyone for any money."