Hussie rarely ever draws the trolls with ears in canon so yeah. He’s drawn them with ears showing in some sketches. 

Pre-retcon Gamzee was killed by Kanaya, he never reached the cherubs. The Gamzee that raised the cherubs was post-retcon. There is no pre-retcon Caliborn since he couldn’t have existed without the recon because the game over timeline didn’t result in a new universe.

She used the juju on Lord English. It’s very likely she was either killed or sucked into the black hole.

No, only the low bloods develop psychic abilities. Vriska’s blood caste is an exception. 

It’s very likely. The horns appear to grow with age.

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