Retcon is short for Retroactive Continuity.  This is the process of changing facts that were already stated.  John is going back and changing parts of the story that were told years ago. And the changes that he is having an effect on how the story will continue to be told, such as Vriska still being alive.

Because Gamzee still killed them.

Gamzee set up their living place and provided food for them so that Caliborn could grow up and become Lord English.  He was also the one that chained them to the sarswapagus 

Not in canon

It’s never said she is in canon. but it also never said she wasn’t. so… to each their own.

I’m aware of that.  I’m sure I have followers who are at all different parts of the story.  But I can’t accommodate all of them.  If you aren’t caught up then following a blog like this has a decent spoiler liability. I can tag asks related to upd8’s as they happen.  But how long after an upd8 do I stop considering it an upd8? 

There hasn’t been an upd8 in nearly two weeks.  But I will do so with future upd8s

I should add ectobiology basics to the FAQ.  That’s a good idea anon.

Yes

Because the harlequin doll that John prototyped only had one arm.