The three major branches of Christianity are Roman Catholic Christians who comprise about 50% of the world's Christians, Eastern Orthodox Christians, which are the second largest branch, and Protestant Christians who make up most of the rest. There are some smaller groups, but they don't comprise a very large portion even combined together.
Roman Catholics and Eastern orthodox Christians and many Protestant denominations like Lutherans and Anglican Christians acknowledge that a figurative first three chapters of Genesis is consistent with our faith.
So yes, most of them.
They accept the Nicene Creed, that was used by Christians as far back as Roman times to define who was a believer. It sums up what Christian orthodoxy is.
One important difference is in the description of the Trinity. Western Christians usually say:
We believe in the Holy Spirit, the Lord, the giver of life, who proceeds from the Father and the Son.
While Eastern Orthodox Christians do not say " and the Son." This "filoque" clause has been a major issue between the Eastern and Western Churches.
You shouldn't have to. Even if you don't accept a figurative Genesis, you are still a Christian as long as you acknowledge the truth of the Nicene Creed.
Actually, the majority of the world's Christians accept that evolution is consistent with God's word. However, it is not a doctrine of His church, so you can disagree with that and still be as Christian as any other in His church.
Of course. The problem is that you're not happy with the way He did it.
And it won't matter to your salvation, even though most Christians don't share your interpretation.
As I pointed out, evolution (change in allele frequencies in a population over time) is directly observed. That's not debatable. We see it happening. On the other hand, common descent, which is a consequence of evolution, is usually what creationists don't accept, and that requires inference from evidence.
So that, I think is really what your skepticism is about. Am I wrong?