How does windowing work in qt embedded, where Qt is drawing directly to a framebuffer instead of through a separate windowing system? Can I run multiple programs at once? Do I get compositing and the little [x] button, maximizing and so forth?
You need to run one application as the server to provide window management facilities; for example, by passing the -qws option at the command line when you run it.
Any other applications are run as clients. See this page for details: