do you want to totally remove xwindows or just change it so xwindows doesn't automatically start? or do you just want a way to kill xwindows when it is running?
if the latter, use 'telinit 3' or possibly 'telinit 2' to get to runlevel 3 or 2 respectively, i am assuming that one of those runlevels will be set to full multiuser mode (meaning you can 'do stuff' but there's no X running unless you startx). try other runlevels if these don't work. viable options are 1,2,3,4 and 5 (or 0 and 6, which are shutdown and reboot respectively and S which is single user mode) i suspect that 3 or 2 are the ones you want though.
Once you have tried that out and found the right runlevel you want, and you've decided you want it to start that runlevel every time you start linux, you need to edit your /etc/inittab -
this page seems quite good at showing this although it deals with editing your inittab so you go from a textual runlevel to a graphical one, and you want the other way round. anyway, follow the instructions and look for the line that says ''id:*:initdefault:' and put the runlevel number you want in where i put that star in.
as for the default shell for a user, try 'chsh' which seems to be the command to change my shell in SunOS4.1 (i can't check it in linux right now, i am at work).
hey btw, how is monkey linux? can it be installed on its own proper linux filesystem on its own partition?