May I know this product power consumption? and What this product use working voltage?

The unit operates on 120 volts (which is the power that is available at an outlet in the USA) and 0.4 amps. As far as power consumption, power is measured in amps. Since Power (measured in watts) = Voltage x Amperage, it would be 120v x 0.4a = 48 watts when in use.I hope this helps.

Not really loud. I use it in my massage room, soft music, candles, etc. totally is fine with a gentle hum.

How powerful is it? I'm a 6'2, 250lbs with strong shoulders.. Will this penetrate deep?

I'm 6'4", 250#, and am returning this product specifically because it does not have enough penetrating power to be worth the $200 pricepoint.

are there still problems with the on/off switch or has the manufacturer corrected it and using this 3 to 4 times a week, how long should it last ?

My Thumper just died, well the switch slides but it won't turn off. This just happened while using it on a patient! But then, it's over 10 years old, and I've dropped it a couple of times. Am buying another today, it's a great workhorse and remained quit all the years I've used it, being about 12 - 15 times per day of a 4 day work week.