yes you can generally use kde apps from any window manager
it's not perfectly threadsafe but should work....
First thing to do I think is just delete the .kde directory in your home directory
rm -R ./.kde
then when you restart it will give you the config wizard and rewrite all the files.
For the other problems I don't use graphical login and i a guessing you are so i can't help alot
if you are using graphical login youu can just do away with it and use startx from the command prompt
go to /etc/inittab and figure out your default runlevel
it will say something like
that means you are booting into run level 3
so go to /etc/rc.d/rc3.d
or wherever yours is and rename all links to gdm, kdm and xdm to start with a '_'
mv S35kdm _S35kdm
like that -- then you will boot to terminal:
logon and type startx
if kde doesn't start
(you might need to create a file in your home directory)
(this is just bare bones -- you can read about this more later)
then when you logout of kde it goes back to the terminal
then just type
if you want to try to still use kdm
there is a file $KDEDIR/share/config/kdm/kdmrc
$KDEDIR is wherever kde is installed
there are alot of shutdown option in there if you are using kdm