1) Yes, Japanese Yen is a currency you can select from within the ClassiPress admin.
2) ClassiPress is a Premium WordPress theme, this means that you need to have WordPress installed on your host account first in order for ClassiPress to work. If this was not what you meant by your question, please clarify :)
3) Yes, we have step by step installation instructions for the theme which you can see some of
here. As a customer you'll be able to read the full page with further configuration instructions.