kstat is the utility used on illumos to query the kernel for various statistics and detailed information. It performs more of less the same responsibly as /proc/ on Linux.
Simply run the command to dump everything:
kstat.exe (output is large)
You can also use it to set certain tunables in the kernel, for example:
To set max ARC size to 512 MiB: kstat.exe -w zfs:0:tunable:zfs_arc_max=536870912
Dump the "zfs:0:tunable" sub-section to list the available knobs to fiddle with.
A setting is not retained over reboot, and will need to be set each boot. (In the future, there will be something to handle this automatically)
The HostID on Windows is generated from the Software/Microsoft/Cryptography/MachineGuid and generally most users do not need to change it. However, should you want to set the HostID that ZFS uses, you can do so by running;
kstat.exe -w zfs:0:tunable:hw_hostid=11223344