not sure how you come to that conclusion. Non-o through an embassy before arriving works well. One could question the sincerity of someone entering on exempt or another visa and then deciding they want a non-o.
Not for year 1. You will need to show 800k in Thai bank account for your first extension. At your next extension you can show 12 conscetutve months of at least 65k into a Thai bank account.
The SSA statements of benefit don't mean anything to the Thai government.
Are your in Thailand? If so get letter from the bank confirming the 800k and bring a 1yr lease agreement and a couple of passport photos and copies of your passport pages. Take all to immigration. Might be best to go to immigration in advance and get their document checklist.
If not in Thailand, use evisa system to apply. Then deposit the 800k when you get here.