Tell us about yourself!
For some one who's first language is not English, this is very well written - until you got right to the end with "6. Conlusion". A typo obviously. I'm a little worried about the suggestion of powering an LED from AA cells with no series resistor - you've already pointed out the risk of frying LEDs that way. You will be OK with button cells as they have limited current output - though you might need 2 or 3 to get enough volts to work an LED. These later options won't work with IR LEDs of course.
Pin 7 is used to discharge the capacitor. So changing the value of the 10K resistor controls how long the LED is lit in each flash. For minimum power use you want short flashes with big spaces between.