Next Steps

Do full wiring diagram for Arduino with RAMPS with TB880 stepper drivers
Use USB power for Arduino
Do not plug in the power to RAMPS - can it be powered only by the USB power via Arduino?
Connect the TB880 with up to 4 stepper drivers each
Use 24v power supply for stepper motors - can the usual steppers handle 24V?
Use AC heater pad so the bed heater is not relying on a DC power supply. This can be done with an external relay activated by the normal RAMPS heat bed output - [1]

Prototyping