It's exactly what they're for.
you cant do that
EV training is a slow process that involves battling specific Pokémon in order to get ev points or effort value points. Most Pokémon give between 1-3 ev points. For every four ev points a Pokémon gets in a stat that stat will be 1 point higher by the time the Pokémon gets to level 100. There is a maximum of 510 total EV points and a maximum of 255 in each stat. When EV training it is important to know which stats you want to raise since you are limited in the total number of ev points both in a specific stat and in total. Maxing out ev's in a stat means getting Pokémon to have 252 ev's in that stat, as that is the highest amount divisible by four. For good ev values for individual Pokémon try the Smogon link below, for good places to train Pokémon in a specific stat check the GameFAQs link. I know this is off topic, but well ev training with bidoofs, i ran into cresselia before i found any bidoofs....
it is impostible
You can get all of the power items at the battle frontier. They cost about 16 battle points. Power items help your Pokemon go faster in the process of EV training.
the pokewalker dosent affect ev points the Pokemon can only gain one lvl per pokewalker stroll so whatever Pokemon your Pokemon battled last will detirmine what ev's it does get
32 to 36 depending on the EV Value
no
no
anorith ev. at level 40 no auto graphs
3 Special Attack
ev training is culmulative, it gathers the points over time which determine how much of a stat boost u get everytime u lvl up. each stat can receive a max of 255 ev points, and a total of 510 ev points for all stats combined. when u reach lvl 100 the most any stat can be raised is by 64 stat points total with a maxed out 255 of ev points on that stat. Pokemon can gain over 64 stat points depending on their base stats and IVs. For instance, my mewtwo(Modest) gained 88 special attack and umbreon(Quiet) gained 66 special defense.
The Vitamins for Black (and White as well) include Calcium (boosts Special Attack by 10 EV's), Protein (boosts Attack by 10 EV's), Carbos (boosts Speed by 10 EV's), HP Up (boosts HP by 10 EV's), Iron (boosts Defense by 10 EV's), Zinc (boosts Special Defense by 10 EV's), PP Up (boosts a selected move's PP by 1), PP Max (boosts a selected move to its maximum amount of PP), and Rare Candies (boosts the level of a Pokemon by 1). Each can be found in multiple areas throughout the game.