Why does it mention their palms?
Malbim: This refers to sins Bein Adam l'Chavero. Kaf refers to the entire hand.
What is "Nego'alu"?
Rashi: It is an expression of filth, like "Lechem Mego'al" (Mal'achi 1:7). Radak - it is a composite of Nif'al and Pa'al; the subject's name is not mentioned.
Which blood sullied their hands?
Radak: Innocent blood that they spilled.
What is the sin of their fingers?
Radak: They send the finger and hit with the fist.
Malbim: The fingers engage in fine Melachos, i.e. individual actions. The culmination of their deeds shows that they were done in Avon, i.e. intentional sin and denial; he sins without concern.
What is the significance of "your lips spoke Sheker"?
Malbim: This refers to sins Bein Adam la'Makom. They spoke false Emunos and De'os.
Why does it mention lips and tongues?
Malbim: Not only did they sin with external speech (lips). Rather, also internally (tongues), they speak and think about mindsets that are false, based on rules of logic. They strengthened [their false beliefs] via misleading proofs.