Can you replace the question mark with the correct number?

Known by all without exception, Forever here, for your protection, Sometimes strong, sometimes weak, Right after the night I come - hot and chic. And while millions of miles away, I always get to you, I find my way. No life around could do without me, Can you guess what I might be?

I know a ten-letter word in the English language which can be typed using only the top rows of the computer keyboard.

Count the number of times the letter "F" appears in the following paragraph:

FAY FRIED FIFTY POUNDS OF
SALTED FISH AND THREE POUNDS
OF DRY FENNEL FOR DINNER FOR
FORTY MEMBERS OF HER FATHER'S FAMILY.

Solve the below puzzle by replacing the question mark with the correct number.

3 6 12

4 8 16

5 10 ?

A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.

Peter wakes up daily to pick up his cycle and crosses the border between Spain and France daily with a bag on his shoulder. He is investigated daily by the officials but they don't find anything suspicious.

If we tell you that he is smuggling something what would it be?

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

Solve below rebus puzzle?

Imagine you are in a room with no windows or doors. How will you get out?