It performs on a par with the Windows version although it will depend on your graphics drivers how well it performs under X. It will hopefully eventually be feature equivalent to the Windows version but that will depend on time and motivation; I see no technical reason why it shouldn't be. Porting to Linux makes a Mac OS X version more viable but it is still another big step and I don't currently have the hardware available to do the port. No idea on release dates; if and when it is ready.
It is a full port to Linux and doesn't use Wine. It is currently a native X or unix app depending on how it is built. There isn't that much difference in the code bases so maintaining different versions is quite easy.