Hi
The terms that you are describing our much more common in a founders/partnership agreement, and less common to an NDA.
Either way, there are a few issues missing in the conditions that you described, 3 of the most important ones being (1) the waiver of Intellectual Property rights, (2) the separating/firing of a founder/contributor and (3) the fact that there is no such thing (in most countries) as a "volunteer" (unless your business is an old age home and the volunteer comes more or less when he wants).
I've successfully helped over 300 entrepreneurs and I would be happy to help you. Good luck