Some visa questions (and thanks very much in advance)

My family and I are starting the process of moving from Nevada to Hua Hin. My wife is a Thai citizen and my 19 year old daughter was born in Bangkok. We moved back to the USA when my daughter was 2 years old so the only Thai ID we have for her is her birth certificate and she has a US passport. My mother and I are American.

Questions: For my daughter, do we need to go to the consulate in Los Angeles to get her a Thai passport, or can she just get a 90 day visa online with my mom and me and then get Thai ID after she gets to Thailand, or can she just show her birth certificate and get a visa on arrival without a return ticket?

How long does it take to get the online 90 day visa, and do we have to wait for my mom to get her US passport to apply.

Would rather not go to LA if possible, long drive, hotel stays, etc But also don't want to have to buy round trip tickets.

Thanks so much!