1)
Is there a difference between "Zarim" and "Aritzim"?
1.
Radak #1: No.
2.
Radak #2: "Zarim" are Nochrim who hate David. "Aritzim" are Zifim.
3.
Malbim: "Zarim" are Zifim, who are not relatives of Sha'ul. "Aritzim" are Sha'ul and his Giborim. They seek to kill me not b'Din, rather, because they are Aritzim (ruthless).
2)
How did they not put Hashem in front of them?
1.
Radak: They did not fear lest he pay to them according to their deeds.
2.
Malbim: They did not heed that Hashem opposes them in this matter.
