There is no general dependency between a "desktop environment" and permissions.
Please be more speciffic or rephrase. What do you mean with "adm user PERMISSIONS"?

This is a really really really bad idea. Don't do it again. Never ever. As said a thousand times before.

For starters:

Just install and use it!
There is no need to do something special. Do not repair, when it's not broken!

lxqt uses the Qt librarys like kde, but it is neither kde nor gnome.
Anyone one can write nonsense in forums - including me of course.
Search: try "adduser", "usermod", "chown", "chgrp" . Adding "linux" or "debian" may improve results. A simple sudo adduser fred is usually sufficient.

Doku:
"devuan" is "debian" without systemd.
General linux: The archlinux wiki is a good source (wiki.archlinux.org), also gentoo.
Search results on "stackexchange" are often helpful for specific questions (it has several sites with different names to sort topics, but the same visual style).

Change DM on debian (e.g.):
sudo update-alternatives --config x-window-manager or
sudo dpkg-reconfigure slim  or sddm, depending on you preferences.

Maybe re-set or re-install lxqt ?
user:
delete or move lxqt-stuff in "$HOME/.config/". Subdir "lxqt", but maybe there is more.
system:
sudo apt purge task-lxqt-desktop
sudo apt install task-lxqt-desktop --install-recommends

Murphy's law in action!
Good to hear.
excalibur seems quite settled by now. I thing I'll give it another try as main system and convert my daedalus again.

Had that issue on my excalibur (test-)installation.
After a few weeks, I just purged it, which caused deinstallation of about 5 other packages.

One possible reason might be the package 'usrmerge'. These days it should be installed before changing to ceres.

This thing is pure apt. Best GUI ever

Auto-mount is usually done by gvfs.
apt install gvfs should do it. Maybe the package gvfs-backends is needed too.

Intresting problem. Google found
https://wiki.debian.org/CrossGrading

One of the steps is adding amd64 architecture, which should allow installing the wanted  (64-bit-)program.

# dpkg --add-architecture amd64

I did not ment to be disrespectful, just that I'm not aware of differences to devuan.

Back to topic.
Just to mention (since I don't like to re-install): It is possible to clean-up an installation using apt-pinning. The wanted release should have a priority of at least 1001 to allow downgrading (apt policy). The steps are in short: adjust /etc/apt/preferences, then apt update; apt upgrage; apt dist-upgrade.

chrony is a possible choice for a ntp daemon. Just install it and you're good to go.

Remarks:
The meta-package ntp (or ntpd) will installs the default time-sync daemon.
I do not know timedatectl. In general, it's a bad idea to install two services for one issue.
In case of a VM: The time comes from the host, so ntp is probably not needed.

(No solution, sorry)
Depending on the time you want to sink in this topic ... something to read.

Detailed information on disk layouts and booting can be found in the install instructions of (e.g.) Archlinux and Gentoo.
Philosophy is: "There is no install program, you do anything by yourself". Instructions and information are corresponding.

"apt pinning" is a possibility. A priority of at least 1001 allows package downgrade.
In your case, It would be pinning the daedalus packages to 1001 and then doing the usual upgrade.
I've done that a few times, it usually just works.

# cat /etc/apt/preferences
Package: *
Pin: release n=daedalus
Pin-Priority: 1001

# apt update
# apt upgrade
# apt dist-upgrade