Two steps down would be 1 step down to D, 1 step down to C.
It's a 5th tuning, just the root and the 5th. Capo at 4th and yer in E, 2nd yer in D. Whatever they did, I don't know, not much of a CSNY guy. I do own a capo so, yeah, just sayin.
So some theory, as I sit here sipping a fantastic cappuccino made by Mrs today.
It's tuned to all roots and a 5th for two things. You've got the drone thing already, you know that one.
Second thing is that most of what we do as Rock Guitar Players is thought out in 5ths, that is, Major/Minor. If you watch my hands play the guitar and you are across from me having to look over to see what the chords are you may get confused because it doesn't look like you think it sounds because I very often don't play the whole chord, just the root and 5th. This makes fat Rock sounds, sometimes erroneously called "power chords". But more important, it allows the melody to determine the mood, the character of the song.
Love The One Your With goes merrily from nice and Major sounding to darker Minor sounding without a hitch. That's because the harmonic content, for the most part, is 5ths. The harmony instruments let the melody determine the dominant feel, that is, a minor third over the 5ths makes for a minor sound, as in the pre-chorus, and a major third over the 5ths makes for a major sound during the title lines.
Listen to the sorta minor sounding aaahhhs with the fairly major B3/Leslie sounds at the same time. The 5ths underneath, Major/Minor harmonic content, allow the two melody parts, those guys singing and whomever mashing the keys, to both be what they are.
It's a thing. Major/Minor is an important concept, I was just going over this with Other Guitar Player in one band. He thought it was magical, and the light went on after 20 years of playing, the parts and pieces moved into place for him. He hugged me. We were both wearing Fedners. Awkward.