Hi silver565,
Sure, I understand why you want hardware RAID....there's nothing wrong with what you are looking for and traditionally HW RAID is the way you would go about getting it.
If you can set aside what you think you want I would encourage you to give ZFS a long hard look. When you have some time I would encourage you to read the obligitory wikipedia link:
http://en.wikipedia.org/wiki/Zfs
and take a look at this presentation:
https://blogs.oracle.com/video/entry/becoming_a_zfs_ninja
I won't regurgitate the above information, but basically ZFS was written by Sun years ago to address a whole bunch of problems with traditional RAID. It's an industrial-grade filesystem that integrates volume management with other features like data checksumming & snapshots. Take a look at it as it solves almost every problem you are looking to address.
I don't know what hardware you are tying to use, but on-board (chipset) raid is really just software raid with a BIOS in front of it so you can boot from it. Neither AMD nor Intel chipsets are supported in FreeNAS which explains why your disks still show up as individual drives. If you use FreeNAS you really only need to worry about the config file, as long as you have a current copy of that you can recover from an OS failure in the time it takes to do a fresh install & restore the config (under 5 minutes if you don't have to burn the CD).
ZFS has the ability to create a special kind of filesystem-within-a-filesystem called a "zvol" that you can present over iSCSI that is direct to disk as you require.
One other thing...you can't present the *same* iSCSI volume to multiple systems without them being "cluster aware". Iscsi looks like a disk that's directly attached to the system so it (rightly) assumes that it has full control of that disk...if 2 systems write to the same iSCSI disk you will almost certainly corrupt the volume.
-Will