microstepping and pwm As per definition:

Micro stepping is a method of moving the stator plug of the stepper motor more smoothly than it is in the full or half step drive mode.The process of micro stepping helps in reducing the vibration and produces noiseless stepping as low as 0 Hz. It even make the step angle smaller and the positioning becomes much better.

Pulse-width modulation (PWM) is a modulation process or technique used in most communication systems for encoding the amplitude of a signal right into a pulse width or duration of another signal, usually a carrier signal, for transmission. Although PWM is also used in communications, its main purpose is actually to control the power that is supplied to various types of electrical devices, most especially to inertial loads such as AC/DC motors.

Which is better method to run a stepper motor with maximum possible speed..?

which can be used to run the motor at almost zero speed ..?

can we be able to rotate the motor at zero or less than Zero speed with PWM method..?

I want to rotate nema 17 stepper motor with microstepping or pwm whichever is suitable and rpm should be greater than what mentioned in the specifications. Can I do this with arduino and any driver..?

which driver would be most suitable to run the stepper at 1000 rpm or more..?
Which is better method to run a stepper motor with maximum possible speed..?


Microstepping


  which can be used to run the motor at almost zero speed ..?


Microstepping


  can we be able to rotate the motor at zero or less than Zero speed with PWM method..?


What is "less than" zero speed? Backwards? Turning through another dimension?  PWM cannot drive a stepper motor. That's like asking if you can download a cake through your suitcase. The concepts just don't match up.  Yes, there are ways of implementing microstepping using closely coupled phase controlled PWM signals, but the end result is microstepping.

A stepper motor requires coils to be activated in the right order and at the right time (and in some cases with the right polarity). PWM just generates a square wave with a set frequency and duty cycle. 

To be clear, a single step of a stepper motor involves cycling through all the correct sequence of energising coils (often a sequence of 4 energisings). Microstepping is merely the act of stopping at different points within that single cycle to give a higher resolution that whole steps (usually 4 times the resolution). It is nothing magical or special.