#1
Im trying to learn scales and have found a site that shows you where to play minor/major scales etc both on the 6th and 5th string. http://robinmay.co.uk/boxes.htm

But im looking at the solo for Pink Floyd's brick in the wall which is in Dm (right?) and it begins on the 12 fret and begins by using only the bottom 3 strings or so...

Can somebody tell me the how this would progress into a full scale?

Sorry if its a dumbass question
#3
Learn your scales all over the fretboard. If the solo is in A minor, it will involve the notes ABCDEFG, no matter where they are.
Someones knowledge of guitar companies spelling determines what amps you can own. Really smart people can own things like Framus because they sound like they might be spelled with a "y" but they aren't.