@oenone: Congrats, you did it. Your phone has a nice huge home partition, is it a 64GB model?
You should flash it to the recovery partition, as @deprecated told you. If your phone has trouble you can use it as described.
Sorry, I wasn't around earlier. Yeah, it's safe to ignore the errors. I've done it a few times as a test procedure on mine, always with the same errors. Glad to see you got it up and running! FYI, you can flash that recovery image to the phone itself with Code: fastboot flash recovery hybris-recovery.img That way, you can enter recovery whenever you need by powering the phone on while holding Vol. down. No more need to use fastboot on your computer each time.
fastboot flash recovery hybris-recovery.img