There are two legitimate possible Christian views on the origin of Adam and Eve. Both are consistent with the information in Genesis 1 and 2. One possibility is that the two of them were created from nothing (the fancy term is ex nihilo). The other possibility is that God took a pair of evolved, intelligent hominids and put in them the image of God. He made them human in the sense that they became like God in certain ways.
Of the two explanations, I prefer the first one. It seems the most obvious way to think about Genesis 1 and 2, but we need to bear in mind that the Genesis creation account is not a scientific one. It is first and foremost a theological one, so exactly how “historical” or “scientific” the biblical description of creation is will be something that legitimate, faithful, spiritual believers can differ on.
Either way, there is clear fossil evidence that there were precursor species around before Adam and Eve, such as australopithecus and homo habilis. These species certainly were not modern humans. Adam and Eve were not of these species. The evidence that nearly human species were in existence between three million and five hundred thousand years ago is fairly strong, and any description of the history of the world must involve these apparent facts. Let me put it this way. It is NOT unreasonable to propose that human beings evolved from a common ancestor to the great apes. Genetic data is also consistent with this possibility.
In my opinion, evolution, including evolution of hominids is supported by scientific evidence. However, I do not believe that Adam and Eve evolved. I believe that they were created ex nihilo. Nevertheless, I accept as equally faithful and spiritual believers who accept description #2 above.
On your second question, it is absolutely okay for a Christian to believe that the theory of evolution is a perfectly good scientific theory for the simple reason that is it a perfectly good scientific theory. For any priest to tell you that it is wrong to believe that the theory of evolution is a good theory is to speak where he probably ought not to speak. Science deals with empirical evidence and competing explanations of that evidence. The fact is that the theory of evolution is the only successful model that exists for the genetic and fossil evidence we have at hand. No other model works. Period. To deny the scientific community the right to come up with reasonable explanations of empirical evidence is a very unwise path, and priests who say this ought to stop saying this. I do not know your religion, but if you are a Catholic, then your church has strongly supported the theory of evolution. If your priest is Orthodox, as far as I know, most Orthodox groups have also been supportive of the theory of evolution, so I am not sure where this priest is coming from.
I have a suggestion. There are two really great books on this topic. One is The Language of God by Francis Collins. The other is Coming to Peace with Science by Daryl Falk. I suggest you read one of these books, as they will help you to understand why I say that the theory of Evolution is a successful theory to explain the origin of species. Both are written by conservative, faithful Christian scientists. Another suggestion is listen to the debate that our group, Apologetics Research Society sponsored titled Four Christian View of Evolution. It is available at www.ipibook.com. Here is a power point from that debate: Evolution Four Christian Views Here is an essay on Four Christian Views of Evolution: Four Christian Views of Evolution