Permanent Resident Alien in US/German Citizen in Oregon needs Visa

I have three questions:
1) I have been invited by a research group at the Chinese Academy of Sciences in Wuhan to attend the opening ceremony of a genetic Stock Center. It's a business visit combined with some sight seeing (I assume). Which visa type do I need? Visa L?
2) I am a German Citizen residing in the US (Oregon), do I apply as a German Citizen or as a Permanent US Resident (Green Card)? What Documents do I use: the German Passport AND Green card or just one or the other?
3) It appears I have to travel from Oregon to San Francisco just to get the Visa. What other options do I have? Can I get the Visa in Oregon?