I need to create a circuit that is a holiday decoration that fullfils two basic components:

1. A solid background consisting of LEDs that is "on" whenever your Power On/Off switch is on and "off" otherwise.

2. A flashing foreground consisting of LEDs that are "on" for a period.

Optional: Create a fade in/fade out feature to the flashing foreground.

I have few questions about this:

1. I initianlly just put an LED via pin 8 to give it the solid background. Is there any other way I can set up the background using an op amp?

2. I am going to put LEDs in parallel (all same LEDs) so that they have the same brightness. Is this a bad practice if so is there any other way to set up the circuit so that I achieve the same brightness for the LEDs?

3. Will a circuit like mine need a capacitor in pin 5? If so, why?

4. Any hints on how to do the fade in fade out feature?

 

Leds need a series resistor to limit current, so if its on a 12v supply use 470 ohms per led all in parallel,for the fade idea i would use the ramp signal from the charging capacitor to feed an op amp and transistor driver.

http://www.allaboutcircuits.com/vol_6/chpt_6/9.html

http://www.555-timer-circuits.com/up-down-fading-led.html

 

That makes sense and by varying capacitor value I can dictate how fast or slow the LED flashes. What about for the background is there anyway for me to include an op amp? I am only given and allowed to use the one op amp and timer that I am given.