1. No problem, you can use it in your email or online name. Many netizens in Japan name themselves like this, ＊＊ちゃん.
Some little stars, when introducing themselves, also say: Hello everyone! Please call me. **ちゃん.
These situations can be used, but in daily life, self-introduction:
こんにちは, private は＊＊です. You can’t say: こんいちは, private は＊＊ちゃんです. You will be laughed at. But you can say, please call me. **ちゃん.
private を＊＊ちゃんとHUんでください. It is very commonly used.
2. TYANN can be typed, but generally it is used: chan
3. Underline is called. アンダーバーunder bar
These are the online names that Japanese girls give themselves, you can refer to them.
/sw/s/room/blog?id=SW31263186
p>http://blog.livedoor.jp/lafontaine/