Just as when the Dragonborn can defeat any dragon and absorb their soul, can dragons do the same (if the DB perished in combat or something)?

Well, according to Arngeir, dragons can absorb the souls of their fallen brethren on the battlefield, so I'm gonna say yes. The Dovahkiin is more or less a dragon in weak flesh.

Yes. The Dragonborn is a mortal man with a dragon soul and dragon blood and just as he can rip out the soul of a dovah because of this, a dovah can rip out the soul of another.

Scary eh? and ofc they loot your backpack too

the moral of this story is: "be unwilling to die!"

Yup.