Hi, so this might be obvious but I seem to be struggling. (Spent ages google and searching Facebook)

We are in Chiang Mai on a 60day tourist visa. Applying for an extension. Got the forms filled in. (UK Citizen)

Do I need a onward travel flight? Do I need to print it out?

Also, should I sign and date all the photocopies or does someone else have to do it?

I arrived in Chiangmai on Oct 23 on a 60 days visa from my home country. The stamp on my passport says it expires on Dec 21. When is the earliest I can extend for another 30 days? I am a US passport holder. Thanks in advance.