Question about which tools to use, bugs, the best way to implement a function, etc should go here. Don't forget to see if your question is answered in the wiki first! When in doubt post here.
Download it, configure it, run it. There is various documentation on the Bochs site, as well as a friendly menu-driven configuration screen.
Am I right that it lets you run your test OS without restarting with a floppy?
Yes. Instead of a floppy disk, you write the disk data to a 1.40MB file, by mounting over the loopback device (on Linux) or using mtools or WinImage to copy files across (on Windows).