How did Vriska take the jacket off her dead corpse when it (and the Quest cocoon Tavros placed her on) exploded when she ascended? And did we ever find out why that happened, given that John and Jade's bodies/beds didn't when they ascended in similar ways?

She didn’t take it she probably made new clothes, as for why is exploded, my guess is because she’s a troll.   ¯\_(ツ)_/¯