Express 48 and 60 as a product of their prime factors. Hence, find the LCM and GCD of 48 and 60.

$48 = 2^4 \times 3^1 \times 5^0$
$60 = 2^2 \times 3^1 \times 5^1$

For GCD, take the lowest power of each common prime factor.
Common prime factors are 2 and 3.
Lowest power of 2 is $2^2$.
Lowest power of 3 is $3^1$.

For LCM, take the highest power of all prime factors present in either number.
Highest power of 2 is $2^4$.
Highest power of 3 is $3^1$.
Highest power of 5 is $5^1$.

The GCD of 48 and 60 is $\boxed{12}$ and the LCM is $\boxed{240}$.

The ratio for Amina : Pauline : Sharon is $2:3:5$.
Pauline's share corresponds to 3 parts of the ratio.
Given that Pauline received 42 sweets, we can find the value of one part:

Sharon's share corresponds to 5 parts of the ratio.

Sharon received $\boxed{70 \text{ sweets}}$.

The base diameter is $12 \text{ cm}$, so the radius $r = \frac{12}{2} = 6 \text{ cm}$.
The height $h = 8 \text{ cm}$.
The slant height $l$ can be found using the Pythagorean theorem:

The area of the circular base is $A_{base} = \pi r^2$.

The lateral surface area is $A_{lateral} = \pi r l$.

The total surface area (TSA) is the sum of the base area and the lateral surface area.

The total surface area is $\boxed{96\pi \text{ cm}^2}$.