Initial questions for final project … they were very broad

1) The human heart is initially similar to a fish heart in the embryo and the hands are initially formed as paddles. Is this a necessary step or is this simply a remainder of the evolutionary history ?

2) When are maternal RNA or proteins deposited into the embryo? Is it before fertilization or after? If it is before fertilization, then at what stage of the egg development are they deposited? If it is after fertilization then what are the mechanisms that signals the mother to deposit them, and how would this work in the case of external fertilization?