Did you have a brand new year of insurance to show? They will only stamp you in until the expiration date of your mandatory insurance if that is less than the 1-year you would otherwise receive.
If you can find an agent that will do everything for you then there's no problem. But many agents have lost the ability to open bank accounts. So if you can't find an agent to do that, you'll need to leave and apply for the non-O from a Thai embassy, and then return with the non-O visa and start from there.
If you went to Laos, you certainly did not get a non-OA visa. That's a visa you can ONLY get in your home country, and it requires insurance, health check, criminal records check, and many other things. The only retirement visa you could have gotten in Laos would have been the non-O visa.
When a single entry visa is issued, it is valid for 90 days. That means you have to enter Thailand within those 90 days. So if the date on the visa says November 9th, that means as long as you enter Thailand by November 9th, you'll receive a 60-day tourist entry stamp.
But there's not really any benefit to having the visa, since most people entering Thailand will get a 60 day visa exempt stamp if they don't have a visa.
You're filling in your departure date as the same date as your arrival. At least I assume that's the problem. Ignore the departure information. It's not required. Leave it blank. As soon as you start filling it out then it becomes required.
Your passport doesn't have to have any minimum amount of time left to apply for an extension (not a renewal). But your extension can never go past your passport expiration date. So if you apply for an extension when you only have 6 months on your passport, you'll only get an extension for 6 months.
Are you asking about applying for a new passport? You can do that whenever you want. That's between you and your government, has nothing to do with this forum or with Thai immigration.
For your extension, you can apply when you have 30 days or less left at most offices, and some offices allow 45 days or less left.
Sponsor letter is only a factor for DTV, and it's only for the spouse or parent of someone filing for a dependent DTV based on the other person's.
There are 2 main retirement visas, the non-O and the non-OA. The non-O visa that most people use does not require insurance.
The embassy might accept proof of 65,000 monthly income but once you get to Thailand and want to apply for an extension you'll either need embassy verified income (many embassies don't do this anymore) or a Thai bank account with 800,000 baht.