Hi Max. Welcome to the Zone!
With Steppers, You can probably live without limit switches, because a stepper will just stall, and not burn up like a servo will. And "soft limits" like you describe are also available in Mach3. However, you MIGHT want some Home switches.
E stop is a completely different thing. You NEED Estop, because the one switch disables all mill movement in an emergency. You also could benefit from a Charge Pump--which disables the steppers if windows goes a little crazy.