Marco chose Vennegoor, because he needed a pinch-hitter. it is either Vennegoor or Huntelaar.
I think Van Persie will go to the WC.
Seedorf got his chance with the other coaches not with Marco, that's why I think that Marco should try him first, and say something about it based on his own experience with him and not with what he saw in the past,
Yes he's on the back-up list, but I think he is not in the squad because of his many yellow/red cards. He got a lot of them because he was too late with his tackling. He always used his speed, technique en aggression. His speed is not what it was before, causing late tackles, which cost him a lot of cards. The last thing you want on the World Cup is a red card in an important match...
I'm not woried about our defence. Because vd Sar is a great gk and Mathijsen and Boulahrouz(their form isn't that great) but I think its a good solid defence. Not as good as Englands thought. Davids brings hart into the game and that is what we need.
I think van Basten's options are fine. A new generation needed to get the breakthrough and establish themselves without the 90's generation. Davids, Seedorf and Kluivert have a great history with the Dutch shirt, but there are times when you need to have something new.
Until van Basten arrived, I thought those guys were going to be called even when they dipped at their clubs, and only be called up because of what they did in the past. Fortunately for Holland, a new team has been successfully built.