transit layover of 16 hours. Want to visit the city. Do I need a visitor visa?

I am an Indian passport holder, and have a valid US entry permit. I will be transiting through Beijing Airport in December. My layover is about 16 hours. I want to go out of the airport and visit the city.

Could you please clarify whether:
1. I need to apply for one beforehand, or can I get a VOA at the Beijing Airport?
2. If I have to apply one, then should it be Transit G or Tourist L?
3. I reside in Florida, but can I apply for it at the Chinese Consulate in San Francisco?