1) When the physical body dies, the ego and consciousness go the astral plane. This implies the astral plane is able to be visited upon organic bodily death. Isn't "death" here a metaphor as Jesus said "let the dead bury the dead?" Therefore only when the person is physically alive and the ego (consciousness) - Self (astral plane) axis can be maintained. Once bodily organic death occurs, ego consciousness has no access to the now departed connection to the astral plane, so the ego perishes as well?
2) Does the astral plane exist outside of human beings? That implies a metaphysical plane outside the experience of the ego-Self axis, and that the ego can travel outside the human body. Jesus said that the Kingdom of Heaven was within us, not on "Churchianity's" false unspiritual plane. With deep meditation we reach the astral plane of Heaven within us. If a physical body is organically dead, then the astral plane is no longer available to the meditator and the ego ceases to exist.
Your two sets of questions arrived close to each other and seem to be asking about similar topics. So I will attempt to answer both of them at one time.
The complex questions you have asked are well-answered in Autobiography of a Yogi, in Chapter 43, “The Resurrection of Sri Yukteswar.” You might want to review that carefully, because it will tell you much more than I can say in this small space.
When the physical body dies, what remains are the astral and causal bodies. Generally speaking, you begin at that point to dwell on some level of the astral plane.
As for the ego, you do take it with you after physical death, into the astral plane. Yogananda defined the ego as “the soul identified with the body.” Since we have 3 bodies (physical, astral, and causal) and for as long as we have any sort of body, in order to exist within it, we must be attached to it, at least to some degree.
So the ego can never cease to exist until it is completely relinquished at the moment final liberation (all 3 bodies are dissolved away).
As we presently exist in human form, we have an astral body which has its own anatomy including the chakras, the nadis (energy channels), the aura, and so on. It is a body of energy and it exists within and around the physical body.
The astral plane is the place we dwell when we are not at the moment in possession of a physical body. So if you are asking if the human body contains the astral plane, rather than the astral body, the answer is no.
When Jesus said that “the Kingdom of Heaven is within you,” he was speaking of the soul which is temporarily contained in the 3 bodies mentioned above. This is true until we “pop the corks of ignorance, in each one of the 3 containers/bodies” and merge back into the great Ocean of Spirit.
This does not happen automatically at the time of physical death, because, even though we have temporarily have lost the physical body, we are still dwelling in astral and causal bodies. Our ego and all unfulfilled desires and attachments still exist and must be dealt with before reincarnation ceases.