right hand

Q: Is it sunnah to hold the glass with both hands while drinking water. What is the sunnah practice?

Q: What is the sunnah way of holding the glass while drinking water-

a) With three fingers of the right hand

b) All five fingers of the right hand

Q: Eating with the left hand is haram. But my grandfathers right hand was injured and now since 45 years he was eating with left hand because he is unable to eat with right hand. Is this correct?