Extended chords generally are fairly equal to their non-extended counterparts when it comes to chord leading.. someone who is more into jazz might be able to handle the specifics of this.. I don't really know to be honest. My thoughts are that if it's an A7.. then that is just as good as AMaj when it comes to chord leading.

The D/F# is called a slash-chord. All it means is that the note following the / is the bass note. When you play a chord, the bass note is always the root note. However, if you want to play a D Major chord with a F# bass note, you have to write it as D/F#.. it's not a F# chord.. it's a D with an F# bass.


||-----|--2--|-----|-----|
||-----|-----|--3--|-----|
||-----|--1--|-----|-----|
||-----|-----|-----|-----|
||-----|-----|-----|-----|
||-----|--T--|-----|-----|


The T is your thumb.. you curl it over the top of the fret board to hold down the F# note on the bottom-E string. In Pink Floyd's "Wish You Were Here", there are two slash-chords. There is DMaj/F# and CMaj/G..

The chord progression goes: GMaj12, CMaj/G, DMaj/F#, Amin. Then it repeats with the C and D swapped around.

I've already shown the D/F#. The other two odd chords are:

GMaj12
||-----|-----|--3--|-----|
||-----|-----|--3--|-----|
||-----|-----|-----|-----|
||-----|-----|-----|-----|
||-----|--1--|-----|-----|
||-----|-----|--2--|-----|

CMaj/G
||-----|-----|-----|-----|
||--1--|-----|-----|-----|
||-----|-----|-----|-----|
||-----|--2--|-----|-----|
||-----|-----|--3--|-----|
||-----|-----|--4--|-----|


Oh and just to clarify: sus = suspended (but you think think of it as substituted because you are substituting the 3rd with something else.. usually usually either the 4th or the 2nd.. hence why you see so many Dsus4's around.. lol)

add = added.. basically you are adding a note to the chord.. So Dadd4 will sound completely different to Dsus4. The chord construction "formula" for DMajor would be 1-3-5, where 1 = D. Then for Dsus4 it would be 1-4-5, and for Dadd4 it would be 1-3-4-5.