1)
What is the meaning of "li'Lshoneunu Nagbir"?
1.
Rashi: With our tongues we will overpower.
2.
Radak: [They said] about our tongues 'we will overpower
2)
What is the meaning of "our lips are with us"?
1.
Malbim: This is in matters Bein Adam l'Chavero - Leshon ha'Ra and deceit.
3)
Why do they say "Mi Adon Lanu"?
1.
Malbim: Since our tongues will overpower with false events to deny Hashgachah, we have no Master in Shamayim, and also we can defeat our colleagues with false lips.