The Summer Song intro was Led Zep, I'd have to think about it awhile to remember which.
Open string pinched harmonic, doesn't matter which string. Reach around and grab the bar, pinch the harmonic, and whammy it. He'll start with the bar depressed, he'll also push up on the bar with his thumb from underneath, all depends on what he's after. Leaves his right hand free to throw up in the air, or mute wound strings, or just plain looks cool because it's different and pure Satch. Helps if your bar is bent like Joe's where it's much closer to the body to begin with, it rides in your hand smoother while picking when it's bent also.