Help:DS-3032 and I-864 fee

Two questions about parents' immigration to US:

1. Mail from US Department of State: can we fill the DS-3032 (choice of Agent and Address) to ask all document be sent to my US address instead of my parents' address in China? (they are currently in China).
2. I-864 fee: only need to submit one $70 fee for my parents? or $70 for my mother and another $70 for my father?

Thank you so much!