You can apply when you are 15 , that is when you finish junior high school. That’s when you can become a shikomi.Shikomi training lasts 6 months to a year. If you are too old to become a maiko you can debut straight as a geiko (for example if you’re 19 or older you’ll most likely debut as a geiko).
Depends if you count only Kyoto geiko or all geisha,since there are geisha in Tokyo too, and in some other places (Osaka,Anjo, etc).
No, I’m not a geisha.
You can visit a henshin studio that will dress you up and put make up on you and you can go out and take pictures like that.