Most of the settings are in:
/Users/****/Library/Application Support/Firefox
****= Your User Name
I don't use Firefox but I am pretty sure Passwords are saved in the keychain, so you also need to move your keychains over, be aware, on the new Install the password and user name needs to be exactly the same for this if you copy those files, it will not work if it's different.
Your keychains are in:
/Users/****/Library/Keychains