all-purpose notification system?

Projects General Guidance
2
  1. Is this possible? Am I going about this the wrong way?

Definitely possible, check the adafruit logshield - Data-Logger Shield for Arduino -

it has a Real Time Clock and an SD card.

On the SD card you should have a file which codes the times, the actions and the text for the LCD.

ANd the Arduino reads this file and does a countdown to the next event on the list.

I would propose using a text file with the following structure: { Date; Time; action; text }

*; 08:00; on 5; wake up!
*; 09:00; blink 12; take the red pill
*; 18:00; blink 7; take the blue pill
*; 22:00; on 12; go to sleep
0101; 00:00; blink all; happy newyear
1504; 09:10; flowers for wife

In pseudocode the [simplified] code looks like:

void loop()
{
  t = getRTCtime();
  if (EventExist(t) == true)
  {
    lcd.println(getEventText(t));
  }
  action = getEventAction(t);
  while (not keypressed())
  {
    do( action);
  }
}

You can extend it by adding lines to the file on the SD card. Once a year you need to check date/time of the RTC.

Get the idea?