Intel Matrix Raid - Design Questions (Abit IP35-Pro)

This is no emergency, yet, but would love to address this before an emergency comes along.

Backstory:
I have just built a computer with 4x500GB Hitachi Deskstars originally intending to solely run a RAID5 setup for reliability. I have always run RAID0 on my previous systems and am addicted to the performance perks. After reading further into the capabilities of the ICH9R southbridge I decided to start over with the system and build a 50GB RAID0 array (named PRIMARY - all 4 drives) for my OS and games (C:\) and the remainder for a RAID5 array (named STORAGE - all 4 drives) for all files (D:\). In Windows disk management the PRIMARY shows as Disk 0 and the SECONDARY shows as Disk 1.

Scenario:
Let's say I lose a drive. I am under the understanding that my PRIMARY array will be toast (per usual RAID0) and that I'll need to re-install the OS once a pop in a new drive. I am also understanding that it will need to be recreated (not rebuilt). Also, I'm understanding that my STORAGE array can be rebuilt.

Question #1:
Most important. Is recreating the PRIMARY array possible without impacting the ability to rebuild the STORAGE array?

Question #2:
If I recreate the PRIMARY array, will it appear now as Disk 1 (or even 2) rather than Disk 0 as it did before. I absolutely do not want windows assign a drive letter of D:\ during the OS installation. The way I normally get around this with single drive setups is to disconnect the drive I don't want before installing. The only way I know how to "disconnect" the STORAGE array would be to delete it. Is there a workaround or worry here? Can disk order be manually assigned?

Question #3:
Is there any other scenario that you would recommend for my setup? Would RAID0+1 on PRIMARY be better for me, etc? I'll sacrifice an extra 50GB, but whatever the case, it would need to equal the performance of RAID0, otherwise I will simply revert to RAID5 for the whole system.

Thanks in advance.