Just a quick comment to #3:

One-shot signal handling (the way you attribute to Win32) is also the traditional way on Unix -- I know it was used on older versions of System V (prior to svr3) and I'm pretty sure that many of currently used 'nix flavors inherited it. The ugly thing is that even on systems that use reliable signal handlers (like Linux) you can change this behaviour by adding a simple library to an application at linking time.

And don't even get me started on SIGCHLD differences :)

In short, I agree with tye that it's better to avoid using signals, although from somewhat lower-level reason ;)