Ok for starters this is two seperate questions, however first of all i dont quite understand the theory of open string chords, are they supposed to be triads with four/five notes? i just found out i didnt understand when i was improvising and i realised there are octaved As in an Am Chord, i seem to have overlooked the most obvious chords

Second more interestingly what can people tell me about robert fripps playing aside the bleep bleep frippertronics stuff? How did he get those weird sounds out of his guitar what scales, effects tunings did he use? Especially in 21st century schizoid man?
First question, I don't know.

Fripp was a pioneer, he recorded 21st Century Schizoid Man with King Crimson when effects was still a young industry taking baby steps. The only effects in existence as far as I can remember were the Fuzz Face that Hendrix, Clapton and quite a few other guitar players used, or the Big Muff, also very popular. A few other "fuzz boxes" were available, mostly off brands and not very popular, some really sucked. I think the phase shifter had just barely been invented but i'm not sure, it may have been a year or two later, and a tape loop echo was available, the Echoplex probably the most popular. That pretty much wraps up your choices for effects at the time. Oh yeah, the Cry Baby wah wah was around too, Hendrix used that as well.

Remember we're talking 1969-70 here, not many effects existed...The Beatles were still just barely together, Hendrix died in September '70, Janis Joplin a week later, long hair would still get you pulled over and harrassed by police all over the south, ditto for rednecks everywhere, I was told in a very unfriendly manner quite a few times I needed a haircut, ( a number of those times by my extremely redneck father), and a few offered to do it on the spot with pocket knives - this was a long time ago. The best I could do was shut up and hope I could outrun them, I was small for my age and definitely no fighter. Effects were few and far between.

So out of the available choices, I'd say Fripp used either a Big Muff or Fuzz Face, not much else was available at the time, possibly an echo unit and that's about it since I don't hear a phase or wah on Schizoid Man. I'm pretty sure it's in standard tuning, key of B. April Wine did a cover of the song on Harder Faster in mid 80's, and did a good job of it too, also in B. I've tinkered with the song for years, one really tough one to play.

Even then Fripp was considered a very eclectic and inventive guitar player, experimenting with sounds even Hendrix and the Beatles hadn't dreamed up, the most experimental of the rock groups at the time. Hendrix was quoted as saying he always tried to include something entirely new and different in each album. Considering what they had to work with, I think they did some amazing stuff. People are still trying to figure out how the Beatles got some of the sounds they used on Sgt Pepper's and Magical Mystery Tour...
Hmmm...I wonder what this button does...