Chess Links #2: The 64 Commandments of Chess

I wanted to post this link first, but found that I myself did not understand all the terminology, so I first posted a Link #1 to Chess Terminology.

OK, the link for today is The 64 Commandment's of Chess.  I would appreciate if you discuss some of them with me via comments or messages.  I will, as I go through the list, pose some questions here in cases where I don't fully understand.

31.In the opening, don't remove your Queen from play to "win" a pawn.  What exactly is meant here?  Exchanging the Queen, or parking her somewhere on the side of the board?

48. Is this not a repetition of half of 45?

49. I'm still not too sure of the difference between open and closed games.  Hope I will learn as I go along!

55. To gain space, you usually have to sacrifice time.  Why does this sound like something invented by Einstein? (Ha ha!)

60.  What is meant by "the centre is blocked"?