The "ext4 not found" and "blkid not found" are caused by qole's scripts (I assume they were originally used for the n900 EasyDebian, and have been adapted from there). Both of these errors, however, are not fatal. As to why two different desktops are started, it is possible that you are starting the desktop under a different UID. I am not familiar with the intricacies of Unix account management, but I know that the root account you enter with devel-su is not exactly "real root". The error in starting the chroot from a filebox terminal might have something to do with Filebox setting some environmental variables that interfere with the chroot scripts. There is ext4 support in the kernel (but there's no ext4 module), so you can safely disregard this error.