The only thing that matters with regards to SATA versus IDE is that the older IDE adapters are generally cheaper (and possibly that the newer SATA-SCSI might support drives larger than 2 terabytes - the SCSI-IDE don't). If space isn't an issue, I'd suggest getting a SCSI-IDE adapter and a $12 SATA-IDE adapter if you want to connect SATA.
Speedwise, SATA-SCSI would much more likely be faster than IDE-SCSI because SATA's minimum speed is still faster than the highest speed of most IDE, so if there was even a infinitesimally measurable amount of latency, it'd be less for SATA. But that latency would never be measurable on any kind of SCSI that would ever be available from any m68k machine.
LUN stands for Logical Unit Number. SCSI was a pretty smart protocol for its day (it still is in certain respects) and the standard allowed for eight devices (including the SCSI controller itself) on an 8 bit wide bus, but each device could have a number of individually addressable parts. Some SCSI CD changers used LUNs to select different CDs, some tape libraries use LUNs to select different tapes, and so on. That SCSI card reader uses LUNs to have five different disks all accessible from one SCSI ID.
When machines don't support selecting multiple LUNs (and I'm just talking about booting here - most OSes support multiple LUNs just fine), whatever is at LUN 0 would end up being the thing that can be seen, which is why CompactFlash card is more often put into the PCMCIA slot with the adapter so that it's at LUN 0 and can be used to boot a system.
Speedwise, SATA-SCSI would much more likely be faster than IDE-SCSI because SATA's minimum speed is still faster than the highest speed of most IDE, so if there was even a infinitesimally measurable amount of latency, it'd be less for SATA. But that latency would never be measurable on any kind of SCSI that would ever be available from any m68k machine.
LUN stands for Logical Unit Number. SCSI was a pretty smart protocol for its day (it still is in certain respects) and the standard allowed for eight devices (including the SCSI controller itself) on an 8 bit wide bus, but each device could have a number of individually addressable parts. Some SCSI CD changers used LUNs to select different CDs, some tape libraries use LUNs to select different tapes, and so on. That SCSI card reader uses LUNs to have five different disks all accessible from one SCSI ID.
When machines don't support selecting multiple LUNs (and I'm just talking about booting here - most OSes support multiple LUNs just fine), whatever is at LUN 0 would end up being the thing that can be seen, which is why CompactFlash card is more often put into the PCMCIA slot with the adapter so that it's at LUN 0 and can be used to boot a system.