I have a basic idea of what EV Training is and how to do it, but I need to know a couple of things.

1) Can I EV train with a poke that is at lv 100 already?
2) If so... how can I see the stats improve?
3) What do EVs have to do with IVS?
4) How do I figure out IV's?

If someone can give me an idea to get the best stats for my pokes and all that stuff by explaining IV's, Natures, EV's and anything else.
THANKS, AND MAYBE THIS COULD HELP OTHERS AS WELL

~Rob