Evolution has a large number of concepts though and it infers a Big Bang and a Spark of Life for it to work. While you won't get me biting on those two tickets, I know evolution is solid science. I think a lot of Creationists would bite on evolution if the spark of life wasn't part of the equation. I mean Creationism says how it all started, and evolution says how everything is changing since it began. Just looking at it that way it makes sense. While I can't tell you how old the world is, I can rest assuredly say that evolution works in this post fall of man world.
No, actually the big bang cannot be inferred from evolution. One can infer that the earth must have been around more than 6,000 years as evolution needs some time to account for all the changes documented in the fossil evidence.
However, historically, the discovery was the other way around. That the earth was very old was a discovery of geology. That opened the door to the possibility of evolution. In fact, one of the influences on Darwin was reading Charles Lyalls'
Principles of Geology which he took with him on the
Beagle. So historically it was evolution that was inferred from an old earth, not an old earth that was inferred from evolution.
Furthermore, at the time, the scientific possibilities included a universe that was infinite in time and space, not one that was finite and had a definite beginning. A universe with a beginning was a religious doctrine that had no scientific support until big bang was proposed.
Abiogenesis (spark of life) is not really "part of the equation" either though many creationists assume that it is. However, since there is active research into a natural origin of life, I expect this will remain a point of contention. If we do find a natural pathway for life to emerge from non-life we will have a smooth line of causation from the physics of big bang to galaxy and planet formation to the chemistry that gave us simple life and on through evolution to complex life.
The basic problem with creationism is that it cannot reconcile such a smooth line of continuous natural causation with belief in a creator. Creationism needs gaps into which to insert miracles not possible through natural causation. Without those gaps, those miracles, the creationist has no God.