Equality in the Godhead

Let's start with an affirmation of the doctrine of the ontological Trinity, which states that God exists in three persons and one essence. This is a careful way of conveying the following truths: 1) there is only one God; 2) the Father, the Son and the Holy Spirit are all God; and 3) the Father, the Son, and the Holy Spirit are different persons. With the possible exception of a couple technical attributes generally ascribed only to one or another person of the Godhead, and which are aspects of the way God exists in three persons, all those attributes native to God's being are shared equally by the Father, the Son, and the Holy Spirit. In his divine nature, Jesus the Son of God is fully God (John 1:1; Tit. 2:13; 2 Pet. 1:1), possessing all the attributes native to God in his essence, that is, all the attributes that God possesses just because he exists as God. Omniscience and omnipotence are of this category, so that Jesus possesses both, making him equal to the persons of the Father and of the Holy Spirit in knowledge and power.

However, Jesus also has a human nature. Because omniscience and omnipotence are infinite by definition, and because man is finite, man cannot possess these attributes. Thus, in his human nature, Jesus the Man cannot be equal to any of the persons of the Godhead in knowledge or in power. Generally, the Bible speaks of Jesus from the perspective of his human nature, as in the passages you stated. Granted, the distinction between what Jesus knows in his human nature and what he knows in his divine nature is a difficult one to fathom. It is one of the mysteries of the hypostatic union (the union of a divine nature and a human nature in the one person Jesus Christ) that is beyond our experience and normal patterns of thinking.

The question of authority is more complicated. It involves issues related to the hypostatic union, the economic Trinity, and the ontological Trinity. The economic Trinity describes the way in which the persons of the Father, the Son, and the Holy Spirit interact with and relate to one another, as opposed to the ontological Trinity which describes the way they exist. Authority is often described in terms of right and power. Inasmuch as Jesus is divine, he possesses equal power to the Father and the Holy Spirit. His divine right over creation is absolute as well. Moreover, his authority even in his human nature is now absolute over creation. This, I believe, is what Paul was saying in 1 Corinthians 15:28 -- the context specifically refers to Jesus' human nature (1 Cor. 15:21). I believe this is also the perspective expressed in Mark 10:40. It is safe to conclude that all members of the Godhead hold equal authority over creation.

But is there an inter-Trinitarian authority heirarchy? Yes. In the economic Trinity, the Son willingly submits to the Father's authority, and the Holy Spirit submits to both the Father and the Son. Most people would understand this to demonstrate that the Father's economic inter-Trinitarian authority is greater than the Son's and the Holy Spirit's, and that the Son's is greater than the Holy Spirit's. I suppose there might be some who argue that all persons of the Trinity are ontologically equal in authority, while being economically unequal, but I am unfamiliar with anyone who actually makes this case. Equality of authority is not something generally asserted in statements of faith, creeds or confessions.