And in fact it was incorrect to label the planets as metaphors in the first place. They are not. That would be like saying a calander is a metaphor for the seasons, days, months and years. It's not. It's a way to keep track of the seasons, days, months and years. The celestial bodies act in the same manner as a calander except they are much more accurate because they themselves are woven into the web of cycles that they keep track of.
A lot of those questions can be answered with "they are". Some forms of astrology do take the conception date into account. Other questions have already been answered so are completely irrelevant (the ones that see the celestial bodies as having a direct influence on us rather than as a means of tracking and representing the influences. Even wackypedia knows this so I'm not going to continue repeating it. http://en.wikipedia.org/wiki/Astrology Cycles of change that are observed in the heavens are therefore said to be reflective (not causative) of similar cycles of change observed on earth and within the individual.Why are the initial conditions more important than all subsequent conditions for one’s personality and traits? Why is the moment of birth chosen as the significant moment rather than the moment of conception? Why aren’t other initial conditions such as one’s mother’s health, the delivery place conditions, forceps, bright lights, dim room, back seat of a car, etc., more important than whether Mars is ascending, descending, culminating, or fulminating? Why isn’t the planet Earth—the closest large object to us in our solar system--considered a major influence on who we are and what we become? Other than the Sun and the Moon and an occasional passing comet or asteroid, most planetary objects are so distant from us that any influences they might have on anything on our planet are likely to be wiped out by the influences of other things here on Earth.
The rest can be answered if you open your mind to the possibilty that things like the mother's health, the delivery conditions etc are also governed by the same forces that underly the movement of the celestial bodies. All is accounted for in the great web of life, woven by the Supreme Architect.
Ultimatley, your ending quote shows that you are not even willing to change your point of view on the most fundamental part of astrology (the part I put in green!) if you can't change your view point on that then there is little point to this discussion going any further.