Jason,
About what rhythm to practice, I recommend using the "Charleston"
rhythm,
based on the melody to the tin pan alley tune. Play the chord on beat 1
and the and of 2. The rhythm to "Killer Joe" by Benny Golson is another
place this is used. It's a simple pattern that is swing oriented, and by
having one aspect (the rhythm) worked out you can apply your
concentration
to the voicings. Don't try too many at once; take a dominant chord
through
a tune like "Sweet Georgia Brown", or "Sweet Georgia Bright" for that
matter.
About transcribing changes from a record: I find that guitarists tend to
use a lot of the same voicings, because of the structure of the
instrument,
so learning the stock "jazz guitar chords" will help because they crop
up
a lot. I used to practice sounding out each note in any chord I was
learning
and singing the notes, which I think helped me to hear them more
clearly.
Clay