1) Hang:
Don't compile the kernel with realtime preemption but with desktop
preemption and the hang will go away. It's a bug in the RT patch.
Thanks for pointing that one out.
2) QJackCtl:
start qjackctl after starting jackd with the freebob backend on the
command line
or
use qjackctl from it's cvs as it has support for freebob built in.
Done and works!