Yes, I have that hack too.
It has increased the speed of my boot time noticeably, however there's still a largeish delay. I guess CSPPC simply must take its time, and that's it.
Probably. The settings you use (1 LUN for the used unit, NO LUNs for other units) seems optimal. At least that is what was the fastest with my BPPC SCSI.
However, at least with BPPC SCSI you could also tune the SCSI reset delay, I had it set to 1 second IIRC.