Is Espruino right for my project?

Perfect :) I will convert that over.

And all this sort of code will run quite happily?

function createDepartureBoard(){
  var c = document.getElementById("canvas");
  c.width = 192*2;
  c.height= 32*2;
  boardCtx2D = c.getContext("2d");

  boardBuffer           = document.createElement('Canvas');
  boardBuffer.width     = 192;
  boardBuffer.height    = 64;
  boardBufCtx2D         = boardBuffer.getContext('2d');
  
  msgBuffer             = document.createElement('Canvas');
  msgBuffer.width       = 2000;
  msgBuffer.height      = 32;
  msgBufCtx2D           = msgBuffer.getContext('2d');
}

boardBufCtx2D.drawImage(msgBuffer,msgXPos,0,192,9,0,msgYPos+1,192,9);