How does a Volunteer Visa work in Thailand, and can I open a bank account or work on it?

You can open a bank account on a visa exempt or tourist visa entry. You don't need a volunteer visa to do it

Okay the 'volunteer visa' that most foreigners here have was gotten by giving an agency/agent your passport and a pile of baht. It was sent to a province you don't live in, used an immigration office you don't go to and a 90 day Non-O visa and then a year extension based on volunteering for a foundation you can't pronounce let alone ever intend to volunteer at is stamped in.

That's it, totally, back-door, under the table

BUT

with that being said they are totally real stamps from real immigration officers at real immigration offices. 🙂

It is what it is and I know easily 50 or MORE people who are on a year extension based on "pretend volunteering" and they have had no problems.

It usually cost about 60K or so to get the 90 day Non-O (30k) and then the year extension (another 30K) that gives you a total of 15 months in country (3+12=15) without any issues.

Thailand visa advisor Is great

You cannot work legally while on a Volunteer Visa - you are meant to be volunteering :-). There are many who do work remotely while on them.

You can work at the organisation you've signed up to volunteer at yes.