Is there a way I can at least login to the terminal to work on this?
The only way I know of is console mode only-
Press Ctrl+Alt+F2 <Or> Ctrl+Alt+f1.
While your in console mode only you might want to run the dmseg
cmd and read through the log.
It might give you more clues as to why your getting the DBus error.
I'm not sure what this means. Try putting the whole message in Google.
dbus-monitor: unable to enable new-style monitoring: org.freedesktop.DBus.Error
Xorg and Plasma may not be playing nice with each other because they may need other dependencies.
Did you install everything that Plasma needs?
Install the plasma-meta meta-package or the plasma group. For differences between plasma-meta and plasma reference KDE Packages. Alternatively, for a more minimal Plasma installation, install the plasma-desktop package.
-::- If you are already running an X server, use a different display, for example Xorg :2 -configure.-::-
Try removing Xorg and Plasma with pacman. Than install dependencies for Plasma and Xorg and than install Xorg and Plasma and reboot.
If that still doesn't help than you might have to reinstall Arch.