Assistence in making weapon mods

[ImNoGhoul]

Hello everyone. I call upon your wise advice ;)

I've been looking at everyone's sweet mods and i just really want in on the action. I'm tossing around ideas about what to make but before i do anything, I need some help in finding what programs to use, any shortcuts I can take and helpful tips on what to do. Also, could you leave some suggestions on what i should make, that would be really radical. I need help with making the model, importing it into the game, placing it in the game (also spawning it on people and traders), making teh firing sounds and possibly a new reloading animation because I hate the in-game animations. Please reply because i really need help.

Thanks :D