[ubuntu] Mounting questions (loop and noload)

Hi all,

I have a 10gb dd file which I tried mounting as read only. I used the following command:

sudo mount -o loop,noexec,ro file.dd /mnt/file

dmesg | tail

[ 3091.778058] EXT4-fs (loop1): write access unavailable, caot proceed
[ 3184.711078] EXT4-fs (loop1): mounting ext3 file system using the ext4 subsystem
[ 3184.711673] EXT4-fs (loop1): mounted filesystem without joual. Opts: noload

sudo mount -o loop,noexec,noload,ro file.dd /mnt/file

Can someone please answer the following:

1) What exactly does noload do in lamens terms? I read that it doesn't load the linux joual? What does that mean?
2) If I had both filesystems mounted and shut down my machine, would it corrupt the dd files? Am I best ruing umount /dev/loop0 after use?

Thanks!