for 12b) will be moving vertically upwards, i think, as the next adjacent particle is highier? gives impression its in phase.
for 13)a)ii) i would say same thing looking at the place next to it? im not sure this is the correct way but surely y shall be vertically upwards and z would be vertically downwards as its in phase with x.
and about the current one, im really sure what its asking, but a coloumb is an amp per second so an As (amp sec)
I dont know how to the second part without my notes (revision isnt going to well :/)