Firstly, if you use LMCE 0810 beta instead of 0710 you probably won't have an issue.
Your problem likely is that the 0710 kernel doesn't have a driver for that RAID chipset. You could disable the RAID hardware completely and allow the motherboard to see the SATA drives directly. Or you could try the CD install method to install Kubuntu 0710 first by manually adding drivers for that kernel (if they exist). But you are better off just using 0810 instead.
BTW, partitions and filesystems are irrelevant with the DVD install, it just blows away the partitions and creates its own.
I don't understand what you mean by the first disk in the RAID is one partition and the others are other partitions. You don't get to choose that with RAID, that's the point. The RAID controller aggregates the disks into 1 "virtual" disk, which you can then partition how you like, but you don't see the individual disks so you can't assign a particular one to be something specific. You can configure the RAID system to have several RAID containers across different disks, so that you can choose to place a partition on a particular set of disks, but if you did that for a single (first) disk, then it wouldn't be a RAID array at all, thus pointless.
A RAID 0 or 1 requires at least 2 disks (and RAID 1 requires an even number of disks), RAID 5 requires at least 3 disks. Personally, I would recommend you keep your media on a separate device like a NAS, in which case the need for RAID at all on your core is fairly low..;.