Just show your O visa to the airline at check in as you do not need a return or onward ticket with a long term visa

It's a Destination Thailand Visa (DTV) and you can extend once in country after your 180 days stay but the paperwork to extend is not worth the effort, it's the same as re applying for the visa. Better to leave the country for a short period then re enter and get a new 180 day stamp.

The tdac doesn't need to have an exit date filled in

No need to fill that section in

@Steve *****

yes you can extend if you meet the requirements for the extension, you will need to get yourself a bank account as you arrive and then deposit 800k baht in it for at least 2 months before applying for the extension, also a phone number and resident certificate from immigration (using TM30 from your accommodation). Then off you go!!

You will only keep the original date you stamped in on. It's doesn't reset the 90 days each time you re-enter

Don't worry no tourist tax so nothing to pay only your electronic arrivals card within 3 days of your arrival.

@Robert ********

foreign exchange transfer

Ask your hotel for a copy of your tm30 go to immigration to get a residence certificates ( need your tm30) once you have this then typically passport and one other form of ID then go try the banks, typically bangkok bank but I'm less familiar with pattaya. You should be good to go as you have a non o 90 day retirement visa. Go deposit 800k baht into the account and then after 2 months of the money being in your account apply for a 12 month extension

Your visa dates are the validity of the visa. You can enter on the last day and get your 90 stamp. The non O visa cannot be extended for 30 days, you can extend for 12 months but you would need to meet the extension requirements