Ventus doesnt know about Master Eraqus death right ?

actually i think he might he probly heard it from terra and aqua but if he doesnt then he'll most likly know when he wakes up

Ven never got the chance to find out. He was whisked away before it happened, and he arrived after Aqua brought it up with Terra, then changed the subject when he did.

He doesn't know about it. All he knows in relation to the subject is that Terra fought Master Eraqus

I don't think, he does. But maybe he over heard Terra and Aqua speak, or maybe he just figured, that Eraqus is gone.

I think he knows because Master Eraqus said that he will defeat Terra then him, but when he saw Terra in the Keyblade Necropol taht automaticly mean that Terra beats Master Eraqus to be there. =)

If Ventus had heard Aqua and Terra talk about what happened to ME don't you think he would have asked about it?

Well, like TerranortXIII had said, only Terra and aqua discussed about Eraqus' death since they were the only ones to know about it. Then when Ventus came Terra just changed the subject.