As for "Perfect Ability to Act", what that means is somewhat more ambiguous than "perfect knowing", but I believe it simply means the ability to make choices and act on them. It is in considering the implications of the Spirit realm's lack of this ability that things become interesting IMO.
Suppose some of the spirits of the spirit realm devised a way to embed themselves or a portion of themselves in the material realm.
The spirit is different than before. Changed. In this way, change is brought to the unchanging NOW of eternity.
In any case, your post and the ideas in it were very creative and original, thanks for sharing.