No. They are not sequential hermaphrodites.
both male and female
it can grow up to 9 inches from head to tail
because green birds (a type of parrot) where kept in captivity until grown into parakeets/budgies/budgerigar.
just like people
You can not. They have to choose to be mates for what the other one does. Kinda like we do. Also, they might be the same gender.
females ar more quiet because they are less territorial towards other birds.
the color is rainbow or black
I don't know if they are called ''claws'' but my parakeets have long nails that can get sharp if you let them grow. If they get too sharp you have to clip them but it is risky and i think it should be left to a vet.
you cant change gender
If the band at the top of the beaks are the same then chances are good they are the same.
Gourami fish do not change gender. Their genders are hard to pinpoint at first, but as they grow it is easy to differentiate between the two. Males are smaller than females, are slimmer in overall girth, and have longer dorsal fins that come out to a point.
You cannot change your gender in AQW unfortunatly :(