Upnotover

SRT Long Distance Train

One way. No problem.

It's worth noting that currently showing up to 3 April. So it will be 4 more days until new appointment dates appear, (4 & 5 April being weekend, 6 is a holiday). However, it never hurts to check daily as cancellations can occur randomly at any time.

I always go online at 1am. I never had any problem getting an appointment.

https://bangkok.immigration.go.th/wp-content/uploads/APPLICATION-FOR-A-LETTER-OF-RESIDENCE-INFORMATION-IN-THAILAND.pdf

I think you may get a 30% refund. But it would be far better to ask SRT for confirmation.

And if you were, apart from how you would get there (maybe hitch on Anutin's rescue flight?), what business is it of of theirs?

Did you already look here......https://th.usembassy.gov/getting-married-in-thailand/

Mine are, to Kasikorn, and are identified as such on the printed statement.

What did you provide to show your physical presence in Laos? Entry stamp/visa?

Agreed. But in actual fact the London Embassy did exactly that a couple of years ago with my non-O application.... "Other request documents: - Flight details showing the applicant’s name, departure date, all flights en route from UK/Ireland/UK territories to Thailand" It was no problem for me as I had a ticket and I don't ever remember seeing anyone else reporting the same issue. But in the OP's case I am certain there would be no problem.

Yes, take old and new passports to the bank and they'll update. This should be done irrespective of whether you need something for immigration.

I'd be tempted to create a new login with the new email address.

You only enter your INTENDED travel information. Many people apply for a non-O in Vientiane without fixed travel bookings as many will enter over the bridge at Nong Khai either by rail or road. You can enter your intended flight information without needing to book anything. You are not required to upload a ticket for this. Your intended travel details do not appear on the Visa.

Well they "recommend" not "require" every 90 days, maybe only cut you off if you ignore that a few times.