In case anyone else cares, I found the answers to my questions:
"The general logic unit (GLU) chip performs support
functions for the microprocessor in the Macintosh II, IIx,
and IIfx. It provides address decoding, chip select, RAM
refresh, CPU, SCC, and VIA clock signal generation and
NuBus, VIA, SCC, power, and NMI switch interrupt handling.
Operating System Support (OSS) Chip
Some of the support functions the operating system support
(OSS) chip performs include I/O device decoding and timing,
interrupt prioritization and masking, a 56-bit system
counter, bus timeout logic, and interface support for the
real-time clock chip."
This is actually sort of confused, above it should read II/IIx/IIcx/Se30 and then list the IIfx above the next heading for OSS, as it is the only Mac with that chip.
"The general logic unit (GLU) chip performs support
functions for the microprocessor in the Macintosh II, IIx,
and IIfx. It provides address decoding, chip select, RAM
refresh, CPU, SCC, and VIA clock signal generation and
NuBus, VIA, SCC, power, and NMI switch interrupt handling.
Operating System Support (OSS) Chip
Some of the support functions the operating system support
(OSS) chip performs include I/O device decoding and timing,
interrupt prioritization and masking, a 56-bit system
counter, bus timeout logic, and interface support for the
real-time clock chip."
This is actually sort of confused, above it should read II/IIx/IIcx/Se30 and then list the IIfx above the next heading for OSS, as it is the only Mac with that chip.