How to build a good Pokemon team?

[Mnementh]

So, I've read a bit about stats and IVs and EVs, but it seems like this is the second step before the first. I thought, the way to start is about thinking which attacks/attack-sets are good for a competetive team and then looking up the Pokemon who can learn these attacks.

Question 1: Is this right, is this a good way to start?

Question 2: Attacks have some stats, power and accuracy. Power probably affects damage and accuracy the probability of the attack to hit the enemy But obviously stats like Defense and attack also influence this. Is there some sort of explanation or a formula, to describe more in detail which effect each stat has on the result?

Question 3: Some attacks have the type special, I assume this means Special attack and special defense is used to calculate the result, am I right?

Question 3: Some attacks hit multiple rounds, like uproar. Is the power meant for each of the attacks or for all attacks added together? Same for attacks with multiple hits in one round, like fury attack.

Question 4: How much should I look after side-effects like poisoning, or should I go simply after max damage and accuracy?

I think the attack-set should be diverse enough, so that I could be effective or at least not inneffective against each of the Pokemon-types. Is this thinking right? After that I should choose Pokemon that canlearn these attacks and hopefully have the same type as the attack, to gain a bonus. I also think I should choose Pokemon with good base stats in the right category, so for moves in category special with high special attack. Is that right? Any other tips to start of developing a good team?