The Alternian sun is referred to as blistering here and only a few trolls can withstand it. 

From Andrew Hussie’s formspring. 

Moonsetter

It says on his introduction page that he suffers from bipolar mood swings. 

Yes, you can see a list here.

This tweet by Andrew Hussie pretty much confirms it. Also, they were obviously very close in [S] Act 6 Act 6 Intermission 5. 

Caliborn’s claymation scene basically told the story of his fight with the kids. During the fight he trapped the Beta kids in his white house-shaped juju and then banished it to the Furthest Ring. After that he fought all the Alpha kids and Gamzee was cut in half. Jake then attacked him with his Hope powers but it wasn’t enough to kill Caliborn. Then Arquius came out of nowhere and got a hold of Caliborn and held him while Dirk used his Heart powers to seal Caliborn’s soul inside Lil Cal. Unfortunately, both Arquius and half of Gamzee were sealed with him as well. This fight most likely takes place further along the current timeline. 

The Scratch is meant to reset the session and it’s conditions to make a more favorable session. 

John initiated the scratch using the needles and the needle kind strife specibus. The Beta kids weren’t erased from existence because they were able to escape their session before the Scratch finished. John and Jade went through a fenestrated window to the Furthest Ring and Dave and Rose traveled there in Derse’s moon. 

You’re forgetting about Arquiusprite which is Dirk’s sprite.