I am Made with Cream

What goes up but never comes down?

What am I?

Which 3-letter word can be inserted into all four lines above to form complete words?

P_ _ _ N T

D E _ _ _ S T

S T _ _ _

C _ _ _ E R

You see a boat filled with people, yet there isn't a single person on boat.

How is that possible?

Figure out how many trailing zeroes are in 1000! 

If 

111 = 13

112 = 24

113 = 35

114 = 46

115 = 57

Then

116 = .....???