I went into the Amphur Office 2 weeks ago and asked what I needed. They told me to come back on the 20th July with the following things:
Certified copy of passport
Marriage Certificate
Wife's ID card
Tabien Barn
4 passport size pictures
Wife
1 friend (witness)
1 Pu yai baan
I arrived at 9 am today. They collected my docs and interviewed my wife, then me, and finally my friend. They asked about time spent in Thailand, education, where I have worked, and how I met my wife. This was conducted in Thai, and all of the details were put onto a word document. After signing several forms, I got my yellow book at 10:30 and my ID card at 11am. Easy!