DNA promoting, DNA and chromosomes, genome and DNA

If DNA during life of an organism could promotes or degenerates based on organism prosperity how the current status of DNA is distributed between cells?

I suppose that any promote/degradation to DNA is not so essential to make for example DNA of newborn almost entirely different to man at the best age. Is there something interesting about promoting DNA regard this fact?

I could not exactly understand how chromosomes works. I understand that genes are part of DNA, DNA is wired around some proteins making up some nucleosomes. I think nucleosomes makes up chromatins that makes a chromosome (in form of chromatin loops). Now comes the problem. Regard to chromosome “X” shape with telomere and each arm end how the chromosomes are connected one to each other?

I suppose that DNA exist only in one copy (in one cell). From start to its end is wired around proteins composing all of chromosomes, isˆn’t it? When one chromosomes start and another one begins?

I also do not understand how could half of chromosomes come from each of parent. I was thinking that DNA helix from both parents will split and then one side/arm from each parent will compose the new DNA. How this work in fact?

Could be said that genome differs from DNA including scaffold proteins?