A cylindrical swimming pool has a diameter of 4.2m and a height of 1.7m. Calculate its volume in litres, given that 1000 cm³ = 1 L.

The diameter ($D$) is $4.2 \text{ m}$.
The radius ($r$) is half of the diameter:

The height ($h$) is $1.7 \text{ m}$.

The formula for the volume of a cylinder is $V = \pi r^2 h$.

Using $\pi \approx 3.14159$:

We know that $1 \text{ m} = 100 \text{ cm}$, so $1 \text{ m}^3 = (100 \text{ cm})^3 = 1,000,000 \text{ cm}^3$.

Given that $1000 \text{ cm}^3 = 1 \text{ L}$.

The volume of water that will fill the pool is $\boxed{\text{23554.7 L}}$.

The inside of the pool consists of the circular base and the lateral (curved) surface area.
Area of the base ($A_{base}$) = $\pi r^2$
Lateral surface area ($A_{lateral}$) = $2\pi r h$
Total area ($A_{total}$) = $A_{base} + A_{lateral}$

Rounding to two decimal places:
The total area of tiles needed is $\boxed{\text{36.29 m}^2}$.

Total area = $36.285 \text{ m}^2$
Cost per square meter = R$54.99/\text{m}^2$

Rounding to two decimal places for currency:
The cost of tiles for the pool is $\boxed{\text{R1995.25}}$.