请教给姐妹办移民问题

I applied for my sister's immigration to US 10 years ago, her priority date is Feb 2010. I looked at Visa bulletin, it's Jan 2010 now.

I want to know:

1. What do I need to prepare now when his PD is current ? I know I need to prepare I-864, what other forms do I need ? Do I submit I-864 here or give it to my sister ?

2. For my sister in China, what documents does she need to prepare ?
Will she need to take them at the interview or should she send them to me , then I submit in US ?

Thanks for advices.