Hibana get's 3 charges/shots (each being a cluster of 3 in a horizontal line). 1 will crete a horizontal line peak hole. Putting 2 above each other will create a vaultable hole. And yes, they are vulnerable to batteries/jammers. However, Bandit's trick won't work, he'll have to have put the batteries down before Hibana starts the fuse.
Yeah, just watched the part of the stream where they explain it. I think it's a cluster of 6 per shot, though, and it seems you can actually shoot each individual pellet out of the six according to the devs. Meaning you have control over the position of each of the 18 pellets, though I haven't seen that in action.