Certified copies are embassy specific. Check with the embassy you are applying with if they are needed. Submit the 500K in a personal bank account statement not a business account.
Do not think it will be that quick. If it does you can still get the 30 days extension easy enough when you are there.. Thailand is already losing visitors to other SE destinations so this move will make things worse
I would not be surprised if there are changes especially to soft power. Im glad i got it but i know there is likely some amendments within the next 5 years.
Non O is a 90 day single entry visa used for retirement, family visits etc. it can be extended when you are in Thailand. Check your local Thai Embassy website for the details. Thailand is welcoming to people from all types of backgrounds.