December 31; today is January 1.

They are a grandfather, father and son.

None. He has three sisters.

Cave

A coat of paint.

All apples grow on trees.

Breath.

Lunch and dinner!

Beauty.

If 'b' is in your hand you are the b-holder (beholder) and "beauty is in the eye of the beholder" (a popular idiom).

the letter e

Neither—they both weigh a ton.

One, two and three.