Ooh ja, that four cheese mussel vibe is addictive. Add a bit of garlic if you please and you're in heaven.

To answer your questions it's difficult to pinpoint what makes it work. I think it's a combination of factors. Anyhow, most of your cake flours will be 00. If I recall correctly it's based on how fine the wheat has been ground. That particular brand you should be able to find at most local supermarkets :)