negative wroteits not my system, so i suggest the obvious, i dont have the time to write LONG replies like you do
if true
then either my response is wrong
elif
contains unnecessary details
else
your response is incomplete
fi
that really helps, if ONLT it was not meant to be sarcastic...
@ Hyperspace
All your troubles was my fault. The obarun-install-themes was bugged and it did a wrong installation of your default .xsession.

So, i explain the correct solution to get sddm working correctly and to get the correct permission:
1) DO NOT TOUCH ANYTHING at the /usr/share/sddm/scripts/Xsession script. Let it by default.
2) be sure ton have exactly this at your ~/.xsession:(replace "<user>" by the good one for you) 
# !/usr/bin/bash

_user=<user>

list=( $(ls -A1 /home/${_user}/.66/conf/svscan@ ${_user}) )
for i in ${list[@ ]};do
    var=( $(</home/${_user}/.66/conf/svscan@ ${_user}/${i}) )
    for j in ${var[@ ]}; do
		export ${j}
    done
done

66-all up
enable your sddm service on the same tree as consolekit and dbus (usually the root tree)and reboot. It should be ok.

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