User blog comment:Insistente/Zangetsu - The Impostor/@comment-11271775-20130625234804/@comment-5398287-20130626023504

I can't answer 1 and 4 without going into speculation territory, but for 2 Ichigo himself noted he saved him in the following chapter, so Kuno's rectified that, for 3 he's had a fake Zanpakuto this whole time.