Here's a suggestion for (2), a 'lodel' application:

// lodel.c

/* Adapted from 'mount/lomount.c', function 'del_loop' in util-linux-ng-2.13.0.1 */

#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <string.h>
#include <linux/loop.h>

int main(int argc, const char ** argv)
{
int fd = -1;

if (argc != 2)
{
fprintf(stderr, "Usage: lodel <loop device>\n");
return 1;
}

if ((fd = open (argv[1], O_RDONLY)) < 0)
{
int errsv = errno;
fprintf(stderr, "loop: can't delete device %s: %s\n",
argv[1], strerror (errsv));
return 1;
}

if (ioctl (fd, LOOP_CLR_FD, 0) < 0)
{
perror ("ioctl: LOOP_CLR_FD");
close(fd);
return 1;
}
close (fd);
return 0;
}

Added 'mv' and 'lodel' utilities to git. Mind checking to see if this is acceptable?
http://projects.archlinux.org/git/?p=klibc-extras.git;a=summary

Looks fine to me (though might it be better to name the 'mv' something like 'rename', so that one doesn't expect too much of it?)