I don't know where you're getting this stuff from but all of these points are wrong, Dave.
No one knows why the Earth is tilted. We creationist believe that it was created that way. The only paradigm from which your objection works is from an atheistic worldview where such phenomena requires a purely natural explanation. From within that paradigm, it is readily acknowledged that at some point in the distant past, the Earth did, in fact, rotate on an axis perpendicular to the plane of the solar system and that something, probably an impact of some kind, caused the tilt. I DO NOT endorse that hypothesis, I simply present it so as to demonstrate to you that the tilt of the Earth's axis is not contradictory to the modern understanding of how the universe works. In fact, if the tilt of the Earth's axis (and/or the observations we see that are explained by such a tilted axis of rotation) is contradictory to anything, its the flat earth model.
Actually, it is very nearly circular. The mean distance from the Sun is 92.96 million miles. At its furthest point, the Earth is 94.51 million miles from the Sun and at its closest, its 91.40 million miles from the Sun. That means, at its most extreme orbital points, it's less than 2% out of round.
Be that as it may, your comment is flatly false. We know, because of Newton's discoveries about how gravity works that we WOULD NOT expect a perfectly circular orbit. In fact, a perfectly circular orbit would DISPROVE Newton's Universal Gravity. There are very specific mathematical reasons why such orbit must be elliptical and cannot be otherwise.
No, one would not think that! Newton rightly said that two bodies orbit around a common center of gravity. The Sun's gravitational wobble is quite complex due to the fact that there are several things in orbit around it. This, by the way, is an observable wobble (with the right equipment) and such orbital wobbles are being used to indirectly detect planets around other stars. The point being that if Jupiter and Saturn and the other planets were not actually orbiting the Sun, as the flat-Earth model states, then no such wobble should be detectable - but it is.
The force of gravity is precisely what we expect it to be according to Newton's Laws and now, even more accurately, because of Einstein's theory of Gravity. In fact, it was Einstien's work that explained the peculiar nature of Mercury's orbit.
How is that ironic?
It's also not quite true. Pluto's orbit is tilted 17° from the ecliptic (plane of the solar system (i.e. Earth's orbit)).
There is no wondering about it. They were clearly, obviously, verifiably, demonstrably discovered! And not all that long ago. Recently enough, in fact, that all (nearly all) of the scientist's original work is documented and still available for us to read. There are translations of it available online and nearly all of the earliest experiments can be recreated and performed yourself. In fact, there are astronomical clubs and societies all over the planet that do exactly that just for the fun of it.
Clete