I'm making some assumptions:

Kim Thayil plays all three parts (not at the same time).
He's playing a very expensive, large-ish Martin.
After the final strum of the final mix of the final playback, the engineer, producer and the band all looked up at each other and said, "Whoa." (But only if they weren't all blitzed on China White. And they probably were.)

Chris is a great story. Cleaned up his act, got off the junk, and went back to his roots: snowboarding and his wife and kid(s). Add the fact that he's got my favorite James Bond song (no, seriously), and I think we can all agree I happen to be a fan.

Just assume everything is essentially an E chord, in some form or another, and an open E chord at that. The refrain is E/D, E/F#-E/C#, E/G#-E/B, etc. It's really a compelling progression, resolved with, melodically on the guitar, Esus-Eb-Esus, Eg#, Ee, which gets us to the E/D of the refrain. Just really sophisticated stuff hidden in what might appear to most as simplicity.

(Keifus is unspeakably gay!)

"Four Sticks" hadn't occurred to me till you said it. That's right on. And you should know by now that I take a great deal of pleasure sharing music that to me is quite special with people I think can appreciate that fact.