Regarding invitation letter-Fatih from Turkey

Hi,

We are Turkish and living in Tokyo. Only me is working but my wife is a housewife. My wife and daughter(2 years 5 months) have just decided to go to China and do not have so much time. She will be going to see her relatives(sister) living in China. They will issue an invitation letter. A few questions we have are as below;

1) Is that possible to take and submit you the electronic file of invitation letter? I mean if the electronic file is acceptable.
2) Is the Invitation letter sufficient for my wife only or it is required both for my wife and daughter?
3) Is the visa fee required for my daughter as well as she is only 2,5 years old? If yes, is the whole amount required or a part of whole amount is required?

Thank you in advance.
Best Regards,
Fatih Gunduz