Relationship of Chords / Scales

Just a revision :

The relationship between notes: 
The major scale is king. It goes like this :
root tone tone semitone tone tone tone semitone root

Numbered as :
1 2 3 4 5 6 7 1

kapeesh?

Being a guitarist you want to think of it as distance between the various numbers. Try not to. Focus on the note indices. Being a guitarist you can focus on the note numbers 1 2 3 4 5 6 7 instead of c d e f g a b.
Just remember the names on the first two strings though. Or have an idea of the note names on the first two strings and you are good to go.

Next.

Common chord progressions : 

1 major chord goes well with major 4 , major chord of 5 and minor chord of 6

Learn where these are if your one is on the 6th string (bar chord on 6th) or on the 5th string (bar chord on 5th). Covers about a 90% of the songs :)

If you start on 6th string:
4th = same chord moved to string 5,
5th = same chord move to string 5 two frets down
6th = minor chord three frets up on string 6

If you start on 5th string:
5th = same chord moved to string 6
4th = same chord moved to string 6 two frets up
6th = minor chord moved to string 6 two frets down

Details? Lookup Diatonic harmonies. And here is a very simple explanation:
http://www.youtube.com/watch?v=fXIEmMDwc7E


Soloing? 
A major scale in key x is equal to a minor scale in 6th of key of x.

For C sixth = A.
Therefore Cmaj = Aminor

Using a capo to simplify songs

Lets do it question answer style:

What is meant by transposing down?
Down means lower in frequency which is up the fretboard.

So if I put a capo on the 1st fret what is the transposition that takes place?
You are going to transpose your chords down by half a step (half a tone ... semitone ... by a half note ... all same things).

So your F needs to be played like its transposed value of half a step .... E.

Why this knowledge is useful?
Say you want to play "Stand by me" as given here http://tabs.ultimate-guitar.com/b/ben_e_king/stand_by_me_crd.htm

Want to use a capo? simple Transpose two half steps to see how you would play it if you were to put a capo on 2nd fret.

Cool way to remember
Since you are moving the capo down the fretboard you are going to need to move the chord shapes up which means transposing down in frequency.