1) Typically, girls are only allowed to wear saris once they have turned into a woman (i. e. had their first menstruation).
2) A sari consists of six yards of material. Often when you buy it, there's a "blouse piece" coming with it. It matches the colours and pattern of the sari and will be turned into the blouse (usually short-sleeved or even sleeveless).
4) In the past, it was fashionable to wear colourful saris and choose a long-sleeved or elbow-length blouse in a neutral colour like white, cream or black.
5) There are two main ways to wear a sari in Sri Lanka:
Firstly, there's the up-country style or Kandyan style where there are no visible pleats and the decorated border is displayed prominently. It's a preferred choice for formal occasions, especially for weddings. Women living in Kandy and the central regions of the island usually wear this style, but others choose it too.
Secondly, there's the Indian style / low-country style that's influenced by the Indian roots of the Sri Lankans. It involves folding the sari into many pleats that are gathered at the front and tucked into the waistband of the underskirt and / or belt. There's a folded, long piece of decorated border falling back over one shoulder.
Below, I'm sharing some personal pictures of me wearing the sari, as per request of Ananya Kiran from the Facebook group Indian Fashionistas. The first two pictures show me on my wedding and homecoming day, wearing the Kandyan style. The third shows me dressed up the Indian way.