1) Affirmative, positive, only in a more certain and stressing manner.
2) A decent song by Beck on his album Guero
1) Person 1: Do you want fries with that?
Person 2: Yes.
Person 1: Are you sure?
Person 2: Hell yes!
2) Hell yes now I'm moving this way, I'm doing this thing
Hell yes now I'm turning it on, I'm working my legs
Hell yes now I'm calling you out, I'm switching my plates
Hell yes now I'm cleaning the floor, my beat is correct