That is a question for a German attorney. Hire one in Berlin/

This is an immigration question. Pass to that area.

Get a California attorney to draft a power of attorney. Send it to Japan. Have you father have it notarized at the US Embassy or consulate. A more...

This is an immigration question. Pass to that area.

This is an immigration question. Pass to that area.

I'm sorry, but your question is so unclear I do not understand what you are talking about. What case? Concerning what? Please redraft.

This is an immigration question. Pass to that area.

This is a UK law question. See my colleague Alexander Ivakhnenko's answer above.

She needs yo apply for a Tourist Visa at the US Embassy or Consulate.

You need to hire a California lawyer to find out. There are plenty in LA.