Instead of the user creating new cells, deleting cells, etc, as Pluto notebook will feel like a single page that you write on. Cell delimitations are figured out by the system.
Is now just deleting an empty line: put your cursor there and press Backspace
Put you cursor at the beginning/end of a line and press Enter.
Arrow keys
Run on Enter makes me a bit nervous in the REPL, so maybe Run on Shift+Enter, and normally cells just stay "dirty", and they all run when you do Ctrl+S (like today).
Not sure - not really necessary since we added interactive stack traces anyways
Nope - two consecutive cells (without output inbetween) feel like one
Just like notion and a text editor - you add an empty cell/line inbetween
Run button inside CodeMirror, at the final line of an expression.
Delete button gone