A BVA granted from a partner visa application has no such restrictions.
The BVA will have full work rights. It does not go into effect until the WHV ends and you are still onshore so you are bound by the conditions of the WHV until it ends. As mentioned above, the only way around it is to have the 820 granted while you're still on the WHV and that will take over with full work rights. We've seen some very fast 820 grants recently but I doubt that will still be the case around when you apply as things seem to me to go quiet towards the beginning of the new fiscal year. Most people wait around a year and a half, give or take a few months in either direction.