What are the steps to bring a Thai spouse to the EU for a long stay visa?

It depends on which country you're talking about. My wife came to Poland on a tourist (Schengen) visa, and once she was there, we applied for her residence permit at the immigration office.

Her first permit was a temporary residence permit valid for three years. After those three years, she was granted permanent residence with no expiry date.

Both of those residence permits gave her full access to the job market, meaning she could work for an employer or start her own business.

Need to say which country because they probably all have different rules .Uk for instance has income/savings rules and language proficiency rules as well

There is no such thing as EU citizenship or residence permit. Nationality or residence permit is always country-specific. Free movement within the EU is a different matter. In our case, the marriage was registered in Finland and Thailand. The application was submitted to the Finnish Embassy in Bangkok and the wife was granted residence in Finland after two months. A residence permit can also be obtained on the basis of work, study and business.

I think process depends on the country. In my case we got married while in Finland with Tourist visa, so documents were directly accepted and residence permit was processed in two weeks.

If marriage would have happened in Thailand first, process would have been translation and legalization of marriage certificate and then applying residence permit from Embassy in Thailand. Queue for that would have been 6 months in my case.

Anyway I would say that getting residency permit was the easiest part as long you have marriage that can be accepted in your country.

And to clarify the original intention was not to get married while in EU. It was to check if dark, cold and quiet country was acceptable for living 😀