OK.
I tried to read all that you worte until my mind went
Either way.I will put forward my theroy.
First:As you said.If i travel back in time and kill myself.
If i kill my self in past.I will not live to be in the future so as to travel back in time and kill myself.
That is.I am already dead in past.Then how come i will live and have an opportunity to go back and kill myself.
So,practically i am nothing. (<that last line made no sense)
Second:Until i believe.Traveling back in future is not possible.Traveling in future is possible.But not as we thing.
Something like what Einstein suggested.If i get into the space ship that were to circle around the black hole at the speed of light.
And in speed time slows.ie. Time Wraps. So, for me circling the hole took only 2 weeks(De to speed of light something) but by that time 20 years might have been passed on earth.So,when you return you are still young while your son is a grandpa