“Metamorphosis is clearly a significant part of troll biology, and therefore ingrained in their mythology. They’ve got cocoons everywhere, and are often likened to insects through biological terms. The wings have nothing (we know of) to do with troll adulthood. But have a lot to do with their perception of what ascension should be, which is the culmination of a pupation process. Which is why some may look to fairies as an ideal, or rule them out as fiction on account of the ideal they represent. Ascended trolls in this game are essentially magical fairies.

Humans do not have a good analog for this though, and enjoy no biological upgrades. Only powers and fashion.”

Unknown

Equius and Nepeta did.  Sollux and Feferi did as well but what quadrant they were in is debatable.

It was actually John that stopped that by taking the Ring of Life  before the Aranea-controlled Gamzee could get it

Because she was dead. Just death means stays dead

The A1 trolls didn’t have a tumor exactly, they had a micro-sized tumor-like device.  As for why they had it  ¯\_(ツ)_/¯, because they needed to?

Then they’d be dead

No, he doesn’t want it back therefore he didn’t get it

They didn’t have time to regenerate before their session was rewritten by their scratch