not sure if anyone is interested, but for completeness...
for (b), if you turn on logging you see:
eigend: : assertion failure: !d.is_null()
eigend: : assertion failure: !d.is_null() from eigend-gpl/piagent/src/pia_dataqueue.cpp:66 () caught at eigend-gpl/piw/src/piw_clock.cpp:240
pity i dont get more of a stack trace, but appears a null data item is being placed on the queue.
anyway, this made me suspect the stringer... and what do i then find? the stringer has been removed from the clarinet rig, in the fingerer experimental setup.
I removed this from my setup ... bang, it works fine. both a) and b) are sorted out
so there really are two issues
i) the stringer, receiving some data it cannot deal with
ii) eigenD spinning out of control when an assertion is thrown? or stringer not coping.. not sure which.
any way i hope it will help someone else out there if they try to hook up the fingering agent themselves