Actually, spin and charge and completely different and unconnected.
superweirdo said:
Ok, you told me that repulsion is caused by electrostatic force. What causes electrostatic force? The Charge? What causes the charge?
Sorry, but that's the last stop on the line. Ask again after a decade or two, and maybe there will be something to add.
Recognize that one can not indefinitely ask "why" and expect answers. The point of science is to be able to explain varied and complex phenomena based on a small set of fundamental truths. Perhaps, some day it can all be reduced to a single concept (there's a large number of scientists that challenge this point of view), but at that point, you could still ask "why" and have no answer.
As for the force (or field) traveling at the speed of light, it's almost the other way round. Light, being a disturbance in the electromagnetic field travels at the speed of propagation of the field.
say if you had an isolated particle and just by observing it (if that's possible) you had to tell whether it was charged or not, without using electromagnitism or anything like that. Can that be done?
How do you intend to go about "observing it"? The way we usually observe something is by bouncing light off of it and interpreting the information contained in this light. It doesn't always have to be light that gets used (you could use electrons, neutrons or even tennis balls, depending on what you want to observe), but the idea here is that an observation requires an interaction. So, it becomes meaningless to speak of observation "without using...anything".