Ah yeah so the way keyboard controls are set up now is pretty weird - we will definitely have full control rebinding later so it makes more sense. But right now the controls are hardcoded, and you can check the README file in the game directory to see the exact controls (Show Manual when launching in Steam).
There are 4 sets of keyboard controls spread out across the keyboard, so theoretically you could play 4 players on 1 keyboard, but it gets really tight. Each control set has its own Start button (WASD is Left Ctrl, IJKL is Right Shift, etc) which is why you needed I/K to navigate the pause menu when you used Right Shift.
Good catch on Enter pausing the results screen effects! Added to our list. Thanks for the feedback :D