-Why we have closed bid system? (Why we don't get to know how much dkp other guys bid?)
Most important reason is to spend as little time as possible for making loot decisions and rather have that time used for clearing some content. When we close bid window, winner and amount of dkp used to win item is announced, and that provide transparency to all of raid members. If you still can't make sense about it, try looking at it this way, do you know what cards other guys have when you play poker? It's exactly the same with closed dkp.
-Why we don't use Loot Council?
Personally, I'm big fan of LC loot system, but I'm well aware that it's kind of a system that is open for different kinds of interpretation, and with that being said those who like to have complains about anything and everything would have valid grounds since LC is highly subjective.
-How do I check my dkp, and how do I bid for items?
To check your dkp status during raid, whisper to Elviss: