1)I know for sending sms  through Internet it would be
pass through smsc(sms center), but I don't know how.
another ways are using gsm modems(see
http://pablo.za.net/gsm.html ) or serial port
connected to cell phone and javacomm-api.
2)I couldn't understand what you're meaning about
csend.exe
3)I've attached a manual doc for lgeiran. if you could
connect your app to YMessenger (I mean sending message
to someone in YMessenger list) it could be a fine
solution for you,Although your app would be depended
on LG HomNet portal.