1)
Who are "ha'Nesogim"?
1.
Radak: This is like "Lo Nasog Achor Libenu" (Tehilim 4:9). I.e. they did not go in His ways and did not guard His Torah.
2.
Malbim: Initially they served Hashem, and later regressed from [serving] him.
2)
How did they not seek Hashem?
1.
Radak: Even though they did not serve idolatry, they said in their hearts that Hashem will not benefit or harm them, and there is no benefit to seeking Him and requesting from Him. All those mentioned here are included in the punishment "stumbling blocks will find them and eradicate them" (3), and the coming verses.
