There isn’t a set amount of times you can get a non O during a one year period. The embassy you are applying through will decide whether to issue you one or not.
You’d probably not have an issue trying for two. Perhaps an issue if more.
If you manage to get the visa I really can’t see you having any form of issue with immigration even with a history of previous entries as you have a valid long term visa to enter. That’s not a given as though it’s up to the individual immigration officer.
While some people have attempted this, it's not advisable as your application may be denied if you're not in the country where you applied. You might also be required to attend an interview at an embassy or consulate.
I’m assuming you have an extension of stay stamp in your passport. If so you’d need to get a re-entry permit from immigration in order to keep that stamp “alive” for when you return.
You can get one at your local immigration office or at the airport just before you fly.
On your return you’ll be given a stamp that matches your current “allows to stay until” stamp.
Also you’d need to do the TDAC prior to your arrival. It allows for up to 3 days prior.
When your visa expires is irrelevant. You used it to get in to Thailand and as it’s a Non B single entry it is now finished.
What matters is the “allowed to stay until” stamp you got. If that’s what you are referring to when you say 4th November then that’s when you can stay until, regardless that you are no longer working.
If you had an “extension of stay” stamp that you got from a local immigration office then when the reason for the extension stops so does your ability to stay unless you switch to any other type of stamp. From what you wrote I’m guessing this isn’t the case.
You will be issued an extension until the validity of your passport. If you happen to be short of the full year then that’s on you for not getting a new passport prior to applying.
Some people choose to do this to “change the date” of their new yearly extension time, because it suits their needs better.
For Ireland it’s handled via the evisa system through the London embassy. Typical turnaround times from there are 3-5 days if you have the right documents.
On issue the visa would be valid for 90 days - meaning you have 90 days to enter Thailand.
On arrival you’d be given a stamp for 90 days.
I’d say apply about 1 month before and that should be alright for you.