I will submit documents for a one yr extension based on marriage in Bangkok shortly and understand it takes 30 days to approve?

In mean time will I be ok to fly in/out Thailand or will that affect application above in any way?

By "in the mean time" do you mean BEFORE you apply or AFTER you receive your '30 day pending approval stamp', as in while you're waiting the interim month to get your yearly extension of stay stamp? I'll answer under the assumption you mean the later.

Unless I am mistaken, you most likely need to purchase a re-entry permit to keep the process alive, BUT again I could be wrong.

I'm sure more illustrious thai visa pundits will weigh in on this and get your question answered.

You can not travel on an extension of stay without a re-entry permit to keep it alive and that will be 1,000 baht single entry or 3,800 baht multi entry. You use that number as your visa number for each return and get manually stamped for the same date as the extension of stay.

Ok thanks guys, both replies were answers I was looking for. Many thanks to you both.