1)
Why does it say both "Adam Beliya'al" and "Ish Aven"?
1.
Malbim: Beliya'al refers to casting off the yoke of Shamayim in Mitzvos Bein Adam la'Makom. "Ish Aven" sins Bein Adam l'Chavero.
2)
What is "Holech Ikeshus Peh"?
1.
Rashi: He goes with crooked lips.
2.
Malbim: This is one of the seven ways in which such a sinner is recognized. He speaks crookedly, against the laws of Chachmah; the mouth hints to Chachmah. The other ways are in the coming verses.