Your set root line in the menuentries all point to the uuid of sda1. The uuid in the error message in your first post is in the else statement in those same Debian menuentries of grub.cfg. That uuid, the one beginning with '69529... is on the linux line of each menuentry:
linux /boot/vmlinuz-2.6.32-5-amd64 root=UUID=69529156-707c-497f-bb71-cf75069e53dc ro single
Change the UUID that is on this line to whatever the correct one is, wherever your boot files are. I've never used RAID so don't know where that would be.
You would also need to change the fstab entry below as it still shows the old uuid.
# / was on /dev/md2 during installation
UUID=69529156-707c-497f-bb71-cf75069e53dc / ext3 errors=remount-ro 0 1
Your blkid command from the last post shows the uuid for md2 as the one you are getting an error on?? You don't appear to have a separate boot partition so running the command: df -h should tell you where root is and that should contain the boot files. If you make any of these changes to test, I would definitely make note of changes as this whole thing doesn't make sense to me. Probably due to my unfamiliarity with RAID. I would think the same uuid would need to be in fstab as in your grub.cfg entries.