Learning Dota 2

Learning Starcraft with Day[9] was a blast. I've been playing league for a bit but the new series is enough for me to switch moba. I'm just wondering about 2 things.

  1. Why isn't there a dota category in the forum (now that we have an entire series about it)
  2. Where to find more info about the dota shop (not itemization, but mechanically)
    1. When to buy
    2. where to buy
    3. when to use the courier / when to walk etc.