This article is from January. It has since been peer reviewed and published in Cell.
But, having been peer reviewed has no bearing on reproducibility unless within this study they were to have multiple independent groups repeat their experiments. Which I don’t think they did. Still, good study I think.
From what AI understood, yes. Scientists are not yet sure exactly what they are, and they have no apparent way to survive outside of a cell like viruses, but they also seem to be more complex than plasmids.