I think I can help you on your second choice if I am hearing you right.
To raise an EV, you fight certain pokemon.
For example, gastly gives you 1 speed EV, and Tentacool gives you 1 special defense EV. 4 EVs in one stat is one stat point gained after level up. For example, if you would normally get +3 special attack, you get +4 instead when you collect 4 EVs.
Currently, only 255 EVs are allowed in one stat, and I think you can only have 510 EVs before they stop being counted.
You can also buy things like protein and iron to increase your stats, but they are expensive.