I think you find it's the G dim with 001212 (similar to a D7) then slide up four frets, then to the barre A. Also for the first part, try a D chord, then hammer on a G note on the E string.

Finally, I'm not sure the Dropped D is a good tuning (tho it's your preference) because with the barre A at the end, you can lift the barre finger to accent the resolution back to the D chord.

And sometime try the F to E, F to E chord progression I suggested in the B part. Good Luck