This should be a triple.
These all should be doubles since they are the same sound
Same sound as 7120|2, 7120|4 but there is fewer notes?
Not quite. If the song is played back, the section beforehand (as you've indicated) is both a kick and a synth hit, while that singular note is just the kick.I can see why there could be confusion, as the synth hit feels like it bleeds into other sections.