1.. since the big bang was an explosion.. the universe looks like an explosion which is sphericalish I think o_O

2.. ok. I do not understand..

3.. well.. they meaure the light coming from the galaxies.. like I posted above "they can't measure the distance between the galaxies.. but they get light from them... the frequency of the light from these galaxies is changing.. it is changing to red end of the light spectrum... the amound of the shift is measured... and that number is called the redshift"

cool thing is that if the universe is expanding then we are expanding at the same rate as everything around us so we can't tell.. but we're expanding too.. whee.. maybe somethings expand faster than stuff around us.. and that causes obesity O_O