You'll understand that we aren't in a position to provide any legal advice as to what should be amended or changed.
Yes, only the term “manager” is defined in the bill. The definition is based on various responsibilities, which aren't cumulative. The definition of a manager comes into play as soon as the public department establishes one of those responsibilities. It's important to mention that the manager cannot be someone employed on a casual basis, so the definition has two facets.
As for the term “owner”, the definition relies on common sense because it's not set out in the bill. Someone is an owner when they have property rights over something. That is likely how the term would be defined.