Well, for your mixer, to solve that problem (as root):
chmod 660 /dev/mixer
and make sure your user is part of the "root" and "users" group. Some find this to be a security risk, but I dont think so.
And on this:
/dev/cdrom /mnt/cdrom iso9660 noauto,user,ro 1 1
why is that 1 1? I've always used 0 0.
But try changing it to "auto", instead of noauto.