User blog comment:Xilinoc/Ch. 681 - THE END TWO WORLD/@comment-3423279-20160708035550/@comment-24531362-20160708041417

I don't think they've all been dead. We've no indication that a deceased Quincy retains their powers.

That second thing is also an interesting question. My theory on that matter is that they act in a similar state to Shinigami. If you recall, the human members of Team Deathberry needed to take on spiritual forms to get to Soul Society during the Rescue Rukia arc. In that state, while they were technically human they acted like Pluses. So, I think if they died there they would have stayed dead. That is the way I believe the Sternritters also behave. I may be wrong, but this theory seems to make sense