> 1. We could only find red ones, no blue ones.

That's' it! I remember once I had a flashing (red) led put in series with
a buzzer. The buzzer was playing noise when the led was on, due to led
changing it's resistance when on/off. you can try to put the blue led in
series to the red flashing one, or maybe hook a transistor too if current
is not enough for the blue one to light or for the red one to flash.

Ale

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.