72 hour visa question?

I have 2 questions.

1. Can I get the 72 hr free entry if I am using 2 different tickets from two different airlines? For example..
Washington D.C -> Beijing - Delta Airlines /// Beijing -> Seoul, South Korea - Asiana Airlines. Two seperate payments.

2. Also, My passport expires 7/17/2017. I'm planning on going to Beijing on 6/24 - 6/26. Would I need to renew my passport??