Answer me this: When should a player start considering what character to be good at?

If you like support and team fight use, Dark Seer is worth a try. I played one round as him and found he was the best thing since sliced bread.

Of course, I'd think you'd want to pick heroes with polar opposite roles to get some varied gameplay. That's just me.

I'm in the same boat, I generally play random characters and find it hard to find one I can play comfortably, having said that, I'm still a complete noob at this game :P

Random is great for leaning heroes, to be a well-rounded player.

I generally liked to play supports. Even when I random QoP , Sniper or Centaur, I'd go for the least carry more support route ( Of course when the team has enough carry ). Tho this only applies when our team is on a higher ground, otherwise that's just screwing the game.