Ok your outside of Thailand ok,so first is o-visa but that's on online ,your own bank account as to have 800,000 buat or equivalent in the local bank ,plus the paperwork for the o-visa ,what you do get into Thailand, go and get a bank account within Thailand (if you can get someone with an account to go with you to help)
No, six months of transactions, and letter saying the money is still in the bank account, all on same day, at chachoengsao immigration office and have 2 sets of photocopies, one for local office and one for bangkok main immigration office