Hi,
5.) Sylvian has shown how to get raw BURSTS from the DSP, maybe he is kind enough at this state to help you in transmitting raw bursts. You could realize the 3rd) with two osmocomBB then... at this point you could even do 4th.
Even more to the point ... there is _no_ _need_ for raw burst rx/tx for this application whatsoever ... normal signalling would work just fine.
Cheers,
Sylvain