Most of these console commands should work for you:
http://wiki.beyondunreal.com/Legacy:Console_Commands#Common_Console_Commands
The quick list of common stuff:
stat fps (FPS counter, haven't tried in KF, but I'd assume it's there)
disconnect (disconnect form a server)
reconnect (reconnect to the last server you were on)
exit (exit the game)
For Admins:
adminlogin {username} {password} (Log into the server in admin mode. User and Pass are set in the config file)
admin servertravel {map-name} (force the server to load the specified map)