You only wanted info and nothing else didn't you?
1.Ev-Effort values are called evs in short. Every pokemon yields some evs. Every pokemon yields evs in different stats. For e.g - Blaziken gives 3 attk evs while aggron gives 3 def evs. If you are playing D/P/Pt then you can use that poketch application which increases a number when you touch the button on the touch screen.Eg If you fought 1 blaziken then you can press the button 3 times to indicate that you have given your pokemon 3 evs in attack. You can find which pokemon gives which evs if you google it. Simple isn't it? You can check serebii for more reference.
2. Your second question is already answered isn't it?
3.
http://www.serebii.net/games/hidden-power.shtml. You can find every thing you want to find about Hidden power here on the above page. I won't advise using HP though as its too complicated!
4.Baton pass is a very good move in competitive battling. It can keep the effects in the battle even if you swithch your pokemon. For e.g.- You have an Umbreon and it knows baton pass as well as mean look. You first mean look it then in the next turn use baton pass. You can switch your pokemon and your opponents pokemon won't be able to switch because of mean look's effect. If you had simply used mean look and switched your pokemon manually then the opponent would have had a chance to switch his pokemon as mean look's effect ended as soon as umbreon was called back by you. Understood? Hope it helps you!