There\'s an incredible lack of decent documentation on HTF. All I could find was a Tutorial which doesn\'t provide any of the following really important information:
The new release 0.9.0.0 of HTF (see http://hackage.haskell.org/package/HTF-0.9.0.0 and https://github.com/skogsbaer/HTF/) hopefully answers all your questions. I'll summarize:
Answer to question 1: See the tutorial, http://hackage.haskell.org/packages/archive/HTF/0.9.0.0/doc/html/Test-Framework-Tutorial.html. It explains how to setup a main module that executes all tests defined in your package, see the section "Test definitions in multiple modules"
Answer to question 2: The documentation of the BlackBoxTest module http://hackage.haskell.org/packages/archive/HTF/0.9.0.0/doc/html/Test-Framework-BlackBoxTest.html now explains in detail what a black box test is and how to use it.
Answer to question 3: The HTF repository at https://github.com/skogsbaer/HTF/ now contains a sample
directory with a complete sample project.