Non-O based on what? There are more than 5 different non-O visa types. We can't answer your question without knowing what you're actually applying for.

@Max *********

because they bribe the immigration officers to bypass the requirements

An agent extension would cost more than a border bounce

You need to make sure you have your old passport and your new passport to give to the immigration officers.

A Non-O visa is valid for 90 days from the day it is issued. So you can start anytime within 90 days of your trip. Generally 45 days is plenty of time.

Are you planning on leaving Thailand within your first 90 days? If not, then you don't need a re-entry permit. Wait until you get the 1-year extension to buy the re-entry permit, because they are only valid until the end of the stamp you purchase them for.

Every tourist entry can get one 30-day extension.

There's supposedly only one officer in all of Chiang Mai that deals with DTV extensions. He is at the main immigration office, not at the satellite office.

@Max *********

is this Jomtien? They've been handing out that note that says it's required for years, but it's not actually required. Many just ignore it without any repercussions. And I assure you those using an agent at that office, or any others, don't have to return to show anything.

Is there any reason you don't apply from home before you go? Otherwise you're going to be spending weeks or months in the country where you want to apply.

In order to apply with dependents, one of you must apply as primary and wait for the entire process to complete. Only one that visa issued can the dependent applications be submitted, as one of the requirements for those is a copy of the fully issued primary DTV visa.

Most people are going to Vietnam recently, though Indonesia is also popular as people can stay in Bali while waiting for the e-visa to be processed.

Your Thai wife shouldn't need anything except her Thai passport.

If you're going as well (you don't make that clear) then you also shouldn't need any visa. Just go visa exempt and you'll receive 60 days permission to stay on arrival. Then go to Vietnam. Then when you return to Thailand you'll receive a new 60 day stamp.