well there's alot of denial, oh well.
"Zetsu Cleaned up": Zetsu only said "This was Sasori's true Form" before turning and leaving, the only reason he went there was to pick up Sasori's ring, both puppets were still there afterwards.
"Sand buried Sasori": Just before Sasori was pinned to the wall, his core popped out and into another puppet that was among the 100 he summoned, even if they were to bury that, they would have only buried a puppet with Sasori's core in it, his Personal puppet would be spared.
"Kankuro's Weak": Well DUH!, his method of attack is puppets, instead of learning new jutsu's, he upgrades a puppet, Sasori would be a perfect puppet for him to show off after not appearing since the ichibi mess.
one more thing, is that round bandaged thing to the left of the puppet (Sasori) meant to be that mizunin's sword.
lastly, those things on his hands arn't flamethrowers, they are cannons that shoot different things depending on the scroll he is using (he used both fire and water)