yes, you can only apply for a visa at your current location even if it’s done online and you’ll have to be in Laos to apply for a tourist visa. You might risk they’ll ask you to upload all your passport pages including blank ones to confirm your location. Anyway visa process or processing time first start when payment is done in cash in Laos.
If you take the second (2) escalator up, go through security and down to immigration you’ll see the Re-entry office in the right corner opposite the immigration desks.
There’s no information indicating anything will change with the 30 days tourist extension. If the exemption goes back to 30 days you’ll have 30 days upon entry and still can apply for a 30 days extension. You can also apply for a 60 days tourist visa online through the Thai embassy in London before you leave.
It’s known that some smaller immigrations don’t do Non O in country but normally they offers to send your application to a bigger district immigration. I’ve seen similar feedback previously from the area you currently stays.
Requirement can vary between immigrations. Best to visit your specific immigration and get handed over their list for applying for a one year extension of stay based on your Non O visa based on retirement.
If you don’t get a affidavit letter from your embassy, you’ll need to prove 800K baht in your account two months prior to your application.