If you are feeding your 5v regulator with 12v you can use a 9v1 zener, the 100nF ( same as 0.1MFD, or marked 104 ) can be a 47nF or better a 220nF .
You don't need a seperate eeprom, this works well to save the data once to eeprom when the power goes off. If you are using v1 just check the EEPROM.read and write instructions.
You can make the variables to save anything you want ( I just showed in the example those that I save )