and get the heat bed - the mounting bolts make levelling the bed a purely mechanical process. Which is dead easy.
mount the spare endstop. do an g28, g29 (g28 homes all axis. do that before the bed tough process). Then all you do is adjust the screws till all the readings are the same - or within a few 100ths of a mm. Do a z=0 from the control panel. job done.