I will try to answer these questions for you.
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The mandala is a more subtle energy than the audio, which is why you can carry it all day without having an overload type of a symptom (usually). The audio is more powerful and could cause an overload if you played it 24/7 (like wearing a mandala). I would say if you are carrying it all day as a mandala it is not necessary to play the audio as you are definitely getting the benefits from it but could consider the audio as more of a booster type effect in this scenario. Some people like mandalas, others prefer audio, and/or a combination of both. I, for instance, carry it as a mandala sometimes, but have it in my daily playlist as an audio so there is no chance of losing momentum.
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This is a smart field that grows with you (and other users) so I think you should definitely talk to it and request the changes you are seeking in your life. This will set your intention by default, and improve your connection to the mandala/energy. Being that it is a smart field, it may direct itself to the areas in your request but it could be that to do so, it has to work on other areas first to achieve your results.
I think all of these NFTs are essentially energetic constructs (like servitors almost) that have an intelligent purpose designed into them. Such that, they will work towards achieving their goal (the programming from Captain) while respecting your overall well-being, work only in your highest good, and not break Universal Law (this is part of the smart aspect)
My two cents anyways.