4: Possibly it will be in a later tutorial. The mechanic is complex enough to be at least world 3 or 4, but a tutorial for it is a good idea.
5: I will look into this, the main reason behind players not being able to move in a terminal is to prevent multiple actions from happening at once.
6: The checkpoint is not a save state, rather an undoable action. The act of *leaving the checkpoint's area* will add a location to undo to. pressing undo while on a checkpoint lets you undo past it if you made a mistake before the checkpoint.
G: Before the next update ill swipe the key-rebinds menu from my other game.
Additional: I agree with the statement made within this message.
Question to you: Have you tried the game? Re-reading you first comment it seems you got that information from the video of world 1.
after the last review, i decided to actually get the game. the premise was cool and with fleshing out would be an awesome puzzle game, but after a few days to forget the solutions from the video, i only made it about halfway through world 2 in about a week. the difficulty curve was a little too tight. one thing i wouldn't change, though, is 2-1. the "accidental" realization of that is masterful.
i would also recommend a baba-like approach where you only need a certain amount of levels completed, and it doesn't matter which.
are you perhaps in need of a playtester?