Which alphabet is a part of our body?

Count the Triangle in the figure given below:

A guard is positioned at the one side of the bridge saying ‘A’. His task is to shoot all those who try to leave from ‘A’ to the other side and say ‘B’. He also need to welcome the person who comes from another side ‘B’ to his side ‘A’. The guard comes out of his post every 1 hour and looks down the bridge for any people trying to leave. You are at side ‘A’ and wish to go to another side ‘B’. you also know that it would take 1:45 hr to cross the bridge. How will you cross the bridge?

Find a 9-digit number, which you will gradually round off starting with units, then tenth, hundred etc., until you get to the last numeral, which you do not round off. The rounding alternates (up, down, up ...). After rounding off 8 times, the final number is 500000000. The original number is commensurable by 6 and 7, all the numbers from 1 to 9 are used, and after rounding four times the sum of the not-rounded numerals equals 24.

I am a type of food that is often found in the fridge and can be white in colour. What I am?
Hint 1: I am a dairy product.
Hint 2: You can spread me on the bread.

I am a normal creature, but I have five hands. I can even have more but even then I will be considered normal.

Who am I?

What is the centre of gravity?

Is the statement valid that it does not matter how much older a sibling is, eventually the younger one will be half as old as the older one?

I am the one who remains awake when you sleep. But I need to rest when you awake. Who Am I?

Eight of us go fourth, not back, to protect our king from an attack. What are we?