0thb in a thai bank account in your name only, that's if your going to live in Thailand.
You have to go to your embassy to get the clearance procedures to say that you are not married to anyone else they will give you the ok and valid passport
A translator that can speak thai and English
You will be given two copies of the wedding certificate
You will need to get one translated into English for your country
When you go to the Amphur you should bring your witness with you
Two, if you are thinking of buying a house in Thailand then you need to know that you cannot own the land, so you have to lease the land the house is on so buy the house and lease for 30 years or 60 years, as for working that depends upon the type of work you are going to do ie teaching English you will need adegree in Thailand and get the job so ibefore you travel to Thailand, or if you are thinking of working from home on your laptop the teaching job you really need to look at visa you will need. But frist I would recommend that you come for a few months and see if you find the place you like to live in and the thai immigration rules before you consider retirement in Thailand