The lead guitar part uses a hybrid picking pattern of 6th's notes played with a finger and pick. Once you get comfortable with the picking pattern on the A chord just move it up the neck to the E and D chords in the same barre chord shape. Also make sure to play your notes super short to get that staccato phrasing.
The guitar chords Bob Marley uses for this song and the classic I, IV, V chord progression in A major. These chords can be played in the open position for acoustic guitar, or you can play the barre chords which I have posted on my website.