請教 AP , 多謝！

EB2, I-140 just approved. I-485 pending. Thinking about applying for AP to go back to China this summer. Questions:

1. Do I need to apply for EAD all together?
2. If I use AP for entry back to the US, does my H1-B status automatically change to EAD?
3. Can I still apply for H1-B entry visa in US Embassy, even if I already have AP? I\'m thinking about using H1B, if answer to question 2 is Yes.
4. How long does it usually take to get AP?

Thanks a lot.