If I wanted fish and ducks, and was going to hire out the job, I'd expect to see that the contractor had successfully put in a few like that before hiring her. I'm going to offer some considerations for you and your family and possibly the contractor. It can be done, it has been done, and it takes some planning and there always seem to be initial "failures" as the system (that's what a healthy pond is) gets going.
One consideration in building a deluxe pond is aeration. I used to work with an organization that assisted people with installing and troubleshooting ponds, so I'll tell you some things I remember from that era.
If the pond will be rainwater/runoff fed, the runoff is going to bring in sediment and whatever was sprayed on the land uphill. Think about where you are planning the pond. Also, that sediment will make the pond more shallow every year, until it becomes a swamp (without intervention).
Duck poop, fish poop, goat poop (what may run off into the pond) will collect unless there is an outlet. For those who have them, ponds that are a wide spot in a stream do better because fresh water is constantly coming in to replace some of the pond water. This is not necessarily happy news for those downstream!
Many built ponds lack proper aeration, and that's a major pain from time to time. The microbes that help break down nutrients (poop) do best with some air churned into the pond all the time. Well, there's an extra expense - installation, maintenance, and energy. If you like projects like I do, then that's a plus! It's an opportunity to set up a solar powered fountain, or perhaps (I love the idea but haven't worked on one) a wind-powered fountain. Wow!
Nutrients build up ammonia in the pond - death to fish. Plants take up that ammonia. It's all a balance. Perhaps you can start with a very small proof-of-concept pond just with fish and plants and learn from that.
Whatever you do, I pray you enjoy it, and that it enriches your life.
One consideration in building a deluxe pond is aeration. I used to work with an organization that assisted people with installing and troubleshooting ponds, so I'll tell you some things I remember from that era.

If the pond will be rainwater/runoff fed, the runoff is going to bring in sediment and whatever was sprayed on the land uphill. Think about where you are planning the pond. Also, that sediment will make the pond more shallow every year, until it becomes a swamp (without intervention).
Duck poop, fish poop, goat poop (what may run off into the pond) will collect unless there is an outlet. For those who have them, ponds that are a wide spot in a stream do better because fresh water is constantly coming in to replace some of the pond water. This is not necessarily happy news for those downstream!

Many built ponds lack proper aeration, and that's a major pain from time to time. The microbes that help break down nutrients (poop) do best with some air churned into the pond all the time. Well, there's an extra expense - installation, maintenance, and energy. If you like projects like I do, then that's a plus! It's an opportunity to set up a solar powered fountain, or perhaps (I love the idea but haven't worked on one) a wind-powered fountain. Wow!

Nutrients build up ammonia in the pond - death to fish. Plants take up that ammonia. It's all a balance. Perhaps you can start with a very small proof-of-concept pond just with fish and plants and learn from that.
Whatever you do, I pray you enjoy it, and that it enriches your life.