The value of acceleration due to gravity

$(a)$ Differentiate between $G$ and $g$.
$(b)$ Is the value of $g$ the same everywhere on Earth? Reason out.
$(c)$ How does the gravitational force between two objects change if the distance between them is tripled?

Find the weight of an $80\, kg$ man on the surface of the moon. What would be his mass on the Earth and on the moon? $(g_{e} = 9.8\, m s^{-2}, g_{m} = 1.63\, m s^{-2})$

$A$ man weighs $600\,N$ on Earth. What is his mass? $(g=10\,m s^{-2})$. On the Moon,his weight would be $100\,N$. What is the acceleration due to gravity on the Moon?

$A$ stone is dropped from the edge of a roof.
$(a)$ How long does it take to fall $4.9 \, m$?
$(b)$ How fast does it move at the end of that fall?
$(c)$ How fast does it move at the end of $7.9 \, m$?
$(d)$ What is its acceleration after $1 \, s$ and after $2 \, s$?

Where will a body weigh more: $1 \, km$ above the surface of the earth or $1 \, km$ below the surface of the earth?