离婚后递485还需要以前的结婚证吗?

Divorced 2 years ago. Now start filing I-485.

The lawyer asks me to provide the original marriage certificate with translation. However, I only have the divorce proof from the court. The original marriage certificate is at my ex-spouse's home in China. Do I really need it?

The lawyer also asks all pages of passport, current and expired copy, including blank pages. Why it is needed?

He also gives me a questionnaire about my ex-spouse's personal info. Is this common? Why it matters?

Thanks!