swlist -l fileset will give you information about software and patches that have been installed using swinstall. It will not show software (like Oracle or patches) that have been installed with their own installation routine.
pvdisplay -v /dev/dsk/cXtXdX will show you information about physical disks on the system.
ioscan will give you info about all the hardware on the system, including processors, memory, disks, etc. Do a man ioscan for switches you can use to get specific info.
Check out this FAQ for additional commands you can use for things like kernel parameters: faq51-1184