I have both US and Thai passport, I have dual-citizenship (Thai and US).
I entered Thailand with a US Passport therefore while staying in Thailand I am an holding an American Citizen. Thus I have to keep notifying the Immigration Office of my extension of 90 days.

Now here's my problem. My US Passport will expires in December 2011, my 90 days period is over on October 12, 2011

I submitted my passport to a university service(Assumption University) which I usually does for the last 2 years, they will renew my 90 days extension.
I submitted the passport 1 week prior to October 12. Now they just informed me that they will not renew my 90days extension because my US passport is expiring before the next 90days extension from October to January.
They told me to contact the US embassy and have them renew my US Passport.

Now, I need to know what documents are required to renew my US passport.

And once I have my passport, can I cross over to Laos using my US Passport as I leave Thailand, and entered Thailand using my Thai Passport so that I will hold a Thai Citizen while staying in Thailand?

If anybody can quickly reply to my question, will be greatly appreciated. Thank you.