I'm not so sure that it is a one-shot. They did mention the Dark Ocean a couple of times throughout this series, but they just didn't do much with it outside of this episode and I think when we learn of Ken's background story. Other than that, it's pretty much a giant plothole, but I think that...
They are ok, but the soul of the band is definitely the singer: Sully, which in my opinion isn't good for a metal band, the guitar licks should be better.
Tantric too...
Apocalyptica doesnt have violins in it... but you can convert cello music into violin music...
you can also convert bass parts for a violin...
i have electric violin :]
Download The Hammer Party. Naow. But its not a cohesive album, its just a bunch of awesome songs.
Listen to it like you have ADHD but listen to it. Its great.