Hi bboy_sonik,

To answer your questions:

1. A command-line hex editing app would be interesting I guess - you can try searching for one if you want.  But RCO editing, depending on what you want to do, will probably be beyond hex editing.  Either case, I don't recommend using batch scripts - they're only really designed for performing batch tasks, not really anything more complex
   
2. Since you've said you've made some complex batch scripts, I presume you've used if and for statements and possibly even variables (eg %1 or %a).  I guess this can be somewhat similar to basic scripting.  It'll probably make learning a language easier.
   Although I despise .NET, I guess the framework is quite good.  I wouldn't start with Visual C++ 6 though - it'll take you a while to get to the MFC at least.  So it comes down to Visual Basic 6 or VB 2005.  Or C if you want to continue using batch conversion.
   
3. As Anger said, PRXLauncher doesn't work for M33 firmwares.
   The icons can be hidden by prepending __SCE__ to their name, for example (my PRXLauncher is restricted to 9 characters) you could name your Snes emulator __SCE__SN - this would be executable by PRXLauncher but would be hidden from the GAME menu.
   
4. Never really looked into vshmain so dunno

You might be interested in Z33's rcotool.  It's a command-line application which can replace icons/sounds/models from RCOs.