To answer your questions:
Q. Is the Xcode 4 preview suitable for production work (ie Mac / iOS release), or should I wait for the final build to come out?
You can evolve in Xcode 4 and move back and forth between Xcode 4 and 3 with the same projects. You must use Xcode 3.2 to submit to the App Store, but it is unclear whether this will be forced or simply errors in Xcode 4 may reject your application.
Mac applications do not go through the application store, so if they are built and deployed, you go away :) Be sure to thoroughly test your deployment platform just in case!
I live and die from my console window. Is this window also integrated in the IDE window, or can I get the console window displayed separately?
It is integrated. You can go to the debugger navigator, or you can "show the debugger area" in the view menu so that it appears under other areas of the navigator.
I cannot post images, but they can be seen at: http://i.stack.imgur.com/8A75R.png and i.imgur.com/hAjqx.png
About the general issues of stability / practicality: my experience is that the new design is really good. Everything is more logical. It still slows down the coding process when you adapt, but I dig a new Xcode and think that I will be faster with it in general.
There are errors, especially if you press the envelope. Using LLDB instead of GDB causes my computer to completely lock, for example: (
If you need to be productive and want to spend less time getting to the App Store right now, Xcode 3.2 is where you should be.
If you want to dampen around and can afford to spend time learning a new design and features when dealing with crashes, then Xcode 4 is very useful. Long-term, this is a big improvement in the current Xcode.