I don't think there would be an "industry standard."
As an example, I work at a large advertising company with hundreds of employees. Body copy must be 10-point or larger; this has been set by the man in charge. If you want to make it smaller, he has to approve it. The reasoning being that if the dimensions of the piece are that small, the copy should just be rewritten. That said, the type size can be changed smaller if the font used is still legible enough.
And small type? For "legal" text, the lawyers have said it can be any size. Just by being there it's meeting legal requirements.
Thanks so much Tom! Really appreciate you taking the time.
Font size for body text can be created by making sure the line isn't too short or too long. The recommended setting is about 70-90 characters per line of text.
You can use the Window>Info panel and select the line of text to see how many characters are used in a line.