Karkat was sending her both pitch and flushed advances. He was also being very immature and possessive. That coupled with Terezi’s stress and depression over the fact that she had to kill Vriska, led to Terezi not pursuing a relationship with Karkat. Karkat later apologized to her during openbound and said he respects her decision concerning him.

The Green Sun is in the Furthest Ring. The Furthest Ring is the space in between sessions. If you travel outside the ring of meteors around your session then you’ll be in the Furthest Ring. Sollux launched the meteor over to the Green Sun so the trolls could meet with Dave and Rose.

The yellow mile was the space between the two Fenestrated Panels, Jake’s and Jade’s. Jade explains why the trip takes so long here.

Because the alpha kids were a part of the beta kids’ session players. Meenah and her group weren’t Feferi’s friends either but they’re in the bubbles because they’re a part of the trolls session players.

That subject isn’t really expanded on in canon. For now we’re left up to our own headcanons until Hiveswap probably explains.

The building was grown from a seed found in the Frog Temple

In the alpha kids’ session, PM and WV throw the two rings into Jade’s volcano. It shoots the Genesis Frog into Skaia and the frog grows into Bilious Slick. The Ultimate Alchemy is complete and the new universe is ready to be entered. Jade has post-scratch Earth in her possession and she plans on deploying it in the new universe for the consorts, carapacians, humans, and trolls to live on. The fate of the sprites is up in the air right now.

In the Furthest Ring Alt Calliope uses her wand to create a black hole, sacrificing herself to destroy the Green Sun. The black hole begins to suck in paradox space. 

In Caliborn’s session, he has conquered Yaldabaoth and claims his juju which is in the red chest. Caliborn then use his juju-breaking crowbar to destroy his godtier clock, effectively giving himself unconditional immortality. His eyes become the flashing pool balls and now he has endless power as well since he completed the challenge Yaldabaoth gave him.

In the dream bubbles, which are about to be destroyed by the black hole, Lord English loses his access to the Green Sun and his eyes turn to 8 balls, ready to be sunk into a pocket so to speak. Vriska uses the juju on him. What the juju does to Lord English is up to your interpretation. Many believe the juju trapped him in the Medium, others think it killed him, and still some believe the juju traps him the the narrative.

We may not get any solid answers on his fate until the epilogue. 

Their actual powers were never really expanded on. The Signless’ visions are a Seer thing. Karkat talks a lot about the aspect here. 

Latula says she understands why Redglare and Mindfang hated each other because she’s Mind player. So she probably understands how her post-scratch self would make a series of decisions that leads to her and Mindfang to bloodshed. 

One of the other trolls may have mentioned his username and she blocked him in case he decided to troll her.

A lusus chooses a wiggler to raise after they emerge from the subterranean caverns. So did Terezi just get left with an egg? Did the egg call to her and she slithered over? Did a carpenter drone leave her next to the egg? Terezi is funny.