Originally Posted by: light487First question is what is this scale:

B C D E F# G A[/quote]
One sharp on F, therefore it is the key of G major. Since it "alphabetically" starts on the B, it is the third mode of G major: B phrygian.

Originally Posted by: light487And the other thing I was just thinking about was that I am actually playing this in reverse.. so rather than the C being a Minor 2nd in the scale, it is actually the Major 7th, as per the following:

B A G F# E D C[/quote]
The order in which you play the notes does not affect their fundamental relationship to each other. You can play those notes in any order you want and it is still the key G major, 3rd mode, B Phrygian.

Originally Posted by: light487
It's sort of like an inverted scale in that sense.[/quote]
You can "invert" a scale in order to play a variation on it, but that will not change it's conceptual tag (or identifying factor).
[QUOTE=light487]Calling the C the Major 7th and the A the Major 2nd, makes a lot more sense to me than the C being a Minor 2nd.

From C to B is an interval of a major 7th. Not the other way around. Similarly, from A to B is a major 2nd, not the other way around. From the B to the C is a minor 2nd (or flat 2). It is what it is. :)
[QUOTE=light487]
I've worked out how to create all the main chords, which I play a lot (eg. A-Maj, A-Min, A-Maj7, A-Min7, and A7), from scale theory.. but after that I start to get confused.. someone deciphered the A-Dim7 for me..

There is also A augmented: 1-maj3-sharp5 (A-C#-E#)
A half diminished (or flat 5 min7): 1-min3-flat5-min7 (A-C-Eb-G)
A fully diminished: 1-min3-flat5-double flat7 (or maj6) (A-C-Eb-Gbb)
A minor-major 7: 1-min3-5-maj7 (A-C-E-G#)
[QUOTE=light487] ... but what about this formula:

1 min3 5 min6 min7

If the root (1) is E, for example, what is the chord that the above formula spells out?

E min7 with an added min6.

Good questions. Hope this helps.