I don't want to be a boy anymore. Is there any way to change your gender once you get off the train in Animal Crossing: New Leaf?
No, you can't change your face or gender after creating your character, you'd have to make a new one. You can however make a new, non-mayor character that is female (they will have to more or less start over with various things like house payments, encyclopedia, catalog).
In addition you can also use a Mii Mask from Harriet to look female (I believe you can use a different gender's Mii mask anyway, I haven't tried). And if you wear a female "dress" type item, your character's animations will actually change to the female animation set (note certain "dresses" are unisex or male clothing; as a male Able will make a comment if you attempt to buy female clothing, those dresses will change your animations). I'm not sure if there is a way for female characters to change to the male animations.
No. You need Shampoodle for this. First get 15 haircuts and Harriet will on the next visit ask you if you want a boys hairstyle or a girls. Choose girls. After you are finished with Shampoodle, go to Able Sisters and buy a skirt or dress. If you already have a skirt or dress, wear it.
You can also make Pro-Designs at Able Sisters. First choose dress and choose your sleeves. Then choose a spot for it (You should save that design first). Then, create it and name it. Then you will pay Mabel 500 Bells for the dress design. Then wear it. Finally, you will look and act like a girl!