If you take regular speed it's about 400 baht per paper and same price for the stamp, if you take express it's about 1000 baht. Just except at they make typo and you have to come back next day.
You asking what exactly? The Khor.ror.22 you can get in any amphur just bring the wife, cost about 20 baht to get a printed copy
If you asking how to open bank? impossible now on visa extempt / tourist visa. Then you need to talk with immigration to covert your extempt entry to non-o
Even if you stayed with family should registered in immigration and gotten your tm30 so now when you go immigration you might face issues maybe not. Best option for you to go down to your local immigration and ask
If you get married before last extension goes out, you can apply a new extension based on being married to Thai that gives you another 60 days. Then you can change your visa to non-o u sure if you can get 1 year on top of that but if not then just go Laos and apply non-o