Question in the use of aria-hidden attribute

All,

I have seen discussions on  the use of aria-hidden attribute. I am still not 100% sure on the correct usage after reading the relevant documentation.

Aria-hidden="true" - from the current block attribute (tag) and children are removed from the accessibility tree. visually, is the information still present if no CSS attributes used?
Aria-hidden="off" - does nothing to the accessibility tree.
Now for aria-hidden="false". Extracted code below (assume CSS attributes are not hiding the content).

    <div id="main" role="document" aria-hidden="false">
</div>

What would occur with the children tags within the above div? would they still be visible to the accessibility tree?

Sean