If by models you mean characters then here's the answer: In story mode you can't, but in the other mode, do this:
1. Pause the game
2. Select "Options"
3. Then, hit "Change character"
Chat with our AI personalities
Go to the menu screen and go to options, then change the language.
No it does not. But Jedi Academy does.
u suck
Assuming you've entered the cheat in the first place, simply enter it again and it will disable the cheat.
Mods are usually contained within a .pk3 file. This file should not be expanded, but placed into your base Jedi Knight II/Gamedata/Base folder. If the file is not a .pk3 file, but a folder containing other files, then this folder should be placed in your Jedi Knight II/Gamedata folder, but the Base folder.