Affidavit of Support questions

I am the Priciple Petitioner for NIW concurrent filing.My wife is applying for 485 with me.

1. Do we need I-864 (Affidavit of Support) for each person?
2. Who is the sponsor?
3. My wife has a permanent job (H-1B), does she still
need Affidavit of Support?
4. According to the instructions for I-864, the
sponsor has to be a citizen or a PR, but of course
neither of us is. Can we still be the sponsor?
5. Can I use I-134 instead of I-864? I heard some
people used it.

Thank you so much!