Oddly, particle physics is involved as well, since the environments near black holes can be tremendously hot, a lot of odd particles can be formed. I don't study black holes directly, but I helped a bit with the STIS observations. In the past I studied supernovae, or exploding stars, and many of those form black holes. Generally though I was involved with studying the immediate surroundings of supernovae, and not what happened in the center. I took on stellar evolution talked about them, and we had a class where we would read current papers and discuss them, and black hole papers were common.
Some theorists think so.
No one really knows. The last I heard, even if they could generate a wormhole, the entrance would be microscopically small, and the gravity inside the wormhole would tear you apart. See my answer above. There is a lot of information about black holes on the web. A good place to start is the list of astronomy links on my web page.