Do you bow with two hands in a 'prayer' position? Not unless you're at the Buddhist temple and also saying "성불 하십시오" 1/
Pre-colonial Korean manners had the two hands just below the bellybutton (men- left over right hand, women- right over left hand).
Currently many Koreans bow with their hands at their sides. 2/
Come to a complete stop, and put your heels together, touching (toes can be pointing outwards like a duck).
How deep? Well... how much do you respect the other person? 90 degrees from the waist is usually excessive. 3/
Also, don't bow too fast. A truly polite bow will be held for a count of 3. A rushed bow is impolite.
4/