A player that spent 6.300 IP to buy a weak champion is in a huge disadvantage compared to someone that bough 3 strong champions for 1.300 IP each. Requiring time to change your choices is unbalanced by definition. A competitive game should reward the player that plays better, not the player that has more free time to stay AFK farming runes.How is it unbalanced? [...] so you need to invest the time.
No, it isn't. You can follow Team SoloMid blog or Elementz blog (I'm not even sure if he still plays...) for more details on that, I won't explain you LoL's metagame.Champion balance is relatively good...
Until Riot Games nerf the fews you own, then you need to buy new ones. Back to my first answer.You don't NEED to own a ton of champions to do well, only a few.