Just went through this, you can come in visa exempt, get a 45 day stamp, you will have to have at least 15 days left on your stamp when you apply for an O visa, you have to have 800,000 in the bank on the day you apply, has to show that it came from an international transfer, if you don't already have a Thai bank account you will have problems setting one up coming in visa exempt, in that case you would be better off applying for a visa at a Thai Embassy, if you have a Thai bank account no problems then, just transfer 800,000 baht into it, for your first extension of stay if you wanted to use the 65,000 a month you would have to have a bank statement with 12 transfers of 65,000 or more