B140i is only supported on SLES as Hewlett-Packard made this driver proprietary so you’re out of luck.
In theory you could compile it on your own and integrate that driver on your openSUSE install but that requires a fair bit of knowledge and making your own driver disk. It would simply be easier to use SLES if you want to use a SUSE based product.
Why? It can. Booting with two independent disks should be fairly simple. Booting in fake-RAID mode may be possible but I’m afraid won’t be supported by installer.
Unless you have good reasons to use fake RAID I’d simply go for two independent disks.
Will this be a system that is connected to the internet serving something, such as a web server?
If not, you could download SLES12 and use that as it will not “stop working” after the evaluation period, it only stops receiving updates after the initial 60 days.
If I were to make a guess automatic degradation of the RAID array and booting from the second disk.
I haven’t used Linux SW RAID in years, does it setup grub for both drives automatically now and manages to boot from a different drive if the other one is degraded and system is rebooted?
YaST detects if installation is on RAID1 and offers to install bootloader on both disks. It needs to be explicitly enabled, it is one check box. BIOS usually will try each disk in order, so should fallback to next available. EFI redundant setup is not automated currently.