Is CommonC++/PortAudio/Vorbis really necessary to use OpenAL++?
No. The only library that is really necessary, is OpenAL. Under Linux, the configure script should autodetect which libraries you have and include them. In Windows, you'll have to do it yourself at the moment. I'm working on a better solution. Here's what is necessary, and when: CommonC++ is needed for any kind of streaming. PortAudio is used for streaming from an input device and the Vorbis libraries are used when streaming from an ogg-file.
Playback is way too fast when streaming. What's up with that?
This is a bug in OpenAL. Either get an older version of it (2002-12-30 or earlier), or make sure that your buffers are of sizes that are multiples of 4096. You could of course also wait for the bug to be fixed in OpenAL..