Using the Monthly Income method... he has to prove monthly income of 65, 000 Baht brought into Thailand Bank from a Foreign source for 12 months prior to applying for the Extension of Stay based on a 90 day single entry O Visa. Since this is not practical - not doable by a first time applicant he cannot use the Monthly Income Method the first time out..
When an O-A Visa holder exits Thailand within the first year and then reenters Thailand the O-A Visa is automatically stamped in for 12 more months. This has nothing to do with an Extension of Stay... different kind of deal.
There is no valid reason for the scrutiny and limitations about accommodations BUT someone in the Thai Government thought it up... and that is what has to be lived with... Comparison... a person on one year non imm. O-A Visa arrives at the same time as a person on a STV - Both Quarantine... Then the O-A person is free to go any place in Thailand and stay at any hotel, condo, villa etc. No forced prepaid bookings, etc. Reports only every 90 days to immigration as normal. Free to move and relocate register a new address... The STV restrictions accomplish nothing except to discourage people from using it..
I have operated my small rent car company for almost five (5) years. If a car renter has only a valid home country drivers license - you will be just fine. Nothing bad will happen to you if in a traffic stop or accidents. I have many instances to draw from. Some rent car companies may require an International Permit/License. I don't because they are too easy to counterfeit.
The Non Imm O-A visa and Extensions of Stay from it - Does require an insurance policy. While the Non Imm O and subsequent Extensions from it Do Not Require Insurance.