Knight?
My heart says Gerson, even though that's probably wrong.
Dess?
Her, Noelle, Asriel, and Kris were out later than they were meant to be in the forest. There was a man behind the tree, and then there wasn't, and there wasn't Dess either. She's still alive.
What are some theories you personally believe?
Kris hijacked the Goner Maker to steal your SOUL for himself. He knows that your SOUL is important somehow, likely due to Catti's occult lessons.
Gaster appearance?
On the main route, only so much as he did in the opening. If you go and fight the schizobosses, you can learn more, but only on the weird route will you get to peek behind the curtain.
What do you think Chapter 3's Schizo will be?
I'm still all in on FRIEND INSIDE ME.
What is Noelle's connection to the Schizos?
Noelle seems to have an affinity for finding secrets and 'breaking' games, as seen with Cat Petterz and Dragon Blazers. This caused her sister to disappear.
Where do you think the remaining three Chapters will take place?
ICE-E's, Hospital, Bunker.
Pluey?
A fake show/character in the TV Dark World. Its Light World form somehow allows you to save in the Light World (maybe a DVD?).
Friend?
A DEVICE made by Gaster. I really liked that RNG Lucky Cat interpretation posted some time ago, but that aside, I think
What's Ralsei hiding from us?
I'm guessing he's hiding lots of Dark World rules that will only be relevant later (see: Roaring). Not just for convenient plot reasons, but also he wants to make sure everyone has a good time.
What's gonna happen with the eggs?
I have no idea. The fact that they stay exactly the same in the Light and Dark Worlds imply they have stable 'meaning' between reality layers, which also means they are the same even in NEO Dark Worlds. Probably a key to getting closer to Gaster.
Why did Toriel leave Asgore?
Failure as a police chief, likely related to Dess's disappearance.
Will Toby ever release Hard Mode?
After Deltarune is finally completed.