You've got a lot of variables to isolate with all those different expansion cards. I'd start by stripping the system down to just the 4091 and hard drive. The core issue you're trying to identify is whether this is an issue with the 4091 in general, or whether it's an issue with these particular builds of the re-implemented 4091, correct?
To your specific points:
1. Not certain what could be going on here, but check your filesystem version. If it's FFS, is it the latest FFS from 3.2? Also check the 4091 jumpers. I think you want switches 4-8 off for maximum performance. Also, I'm not familiar with ZuluSCSI, but if it's derived from SCSI2SD v5.x, that's probably the explanation. SCSI2SD v5 is quite slow, limited to about 1-2MB/s.
2. You probably need to change the tooltype SCSI_DEVICE_NAME in HDToolbox from scsi.device to 2nd.scsi.device. If there are multiple instances of scsi.device, subsequent ones get a "2nd." or "3rd." etc. prefix. Since you have the 3000's onboard SCSI and the 4091 SCSI, I suspect this is what's happening. By default it's looking for devices on the internal bus (scsi.device), which is empty.
3. No idea for this one, sorry.
4. What version of MUI are you using? The only stable version for 68K is good ol'
3.8.
5. Not sure, but active termination is usually a good bet. Anything in the ZuluSCSI docs?
6. RAWBInfo is a standard program that ships with the OS. It's responsible for the enhanced icon information window. It should not be crashing. If it is, it indicates something else wrong with the system - possibly a termination/bus issue. A good test would be to see if the same thing happens with the hard drive connected to the internal SCSI bus. Your IBrowse crashes could be related to the same phenomenon.
I hope some of this is helpful!
