1: BSJB isnâ€™t even out yet if that is what the next firmware is called.
Bitsetting is supported in all of BenQ firmwareâ€™s
There is no official over-speeding in the 1640 firmwareâ€™s yet...
As for TDB firmwares might be for the first early ones not the most recent firmware I think.
2: You can turn off WOPC if you know the media you have is of good quality in order to decrease burn times.
3: Patience, give ala42 time when the next firmware comes out he'll get to it when he's ready.
4: Read over the threads with scans on 1640 media or take a look at the table in this thread.
5: Solidburn is like Plextors Autostrategy the writer learns as it burns the media and can give better results with subsequent burns.