Yes, lightning bending is considered to be the highest level of firebending. It's also hard to tell at first, but Azula has blue fire. She's a perfectionist, and a blue flame is supposed to be a more efficiently burning one. The top knot of the hair is important in Fire Nation culture, you'll notice every Fire Nation male has one. So the cutting of the top knot does symbolize them cutting ties with the Fire Nation
Yes, lightning bending is considered to be the highest level of firebending. It's also hard to tell at first, but Azula has blue fire. She's a perfectionist, and a blue flame is supposed to be a more efficiently burning one.
The top knot of the hair is important in Fire Nation culture, you'll notice every Fire Nation male has one. So the cutting of the top knot does symbolize them cutting ties with the Fire Nation