So, all of the KH2FM cutscenes have now been dubbed and I wonder...

 

Why do Xemnas calls Aqua and Ventus "friend" if his goal is merely to find Ventu's body and use it as a vessel or X-blade related? And why does he spends most of his free time talking to Aqua's armor? Is a part of Terra still inside them, which drives their emotions to look at the past?

Memories can be erease but can still be found in there hearts. When you cant remember people they still feel that they feel them. So probally (Forgotton) Xehanort Still feels Aqua in his heart, but dont remember her.

 

Xemnas is the nobody of Xehanort, and Nobody's still have a tiny piece of his Heart. So Maybe that little pieces includes that He can Feel Aqua.

 

After he saw Aqua's armor he felt it belong to A friend ( He dont'say ''Aqua'' he say Friend''

Xemnas is basically the body of Terra, which by the time grow a heart of his own. That heart was similar to the one he had as Terranort, so a fusion between Terra's and MX's. So some of Terra's old feelings are unwillingly attached to him. In Days, when Xemnas is watching Roxas sleeping he says "So you have gone to sleep again,...friend"

Well, they are using Terra's stolen body, it's possible that despite amnesia that they recognize them enough to know that they may have been friends once. But it's not nearly enough for Xehanort or Xemnas to care about them as friends, just that there are scraps of his memory to be found in recognizing them.

 

Also:

 

Memories can be erease but can still be found in there hearts. When you cant remember people they still feel that they feel them. So probally (Forgotton) Xehanort Still feels Aqua in his heart, but dont remember her.

 

Xemnas is the nobody of Xehanort, and Nobody's still have a tiny piece of his Heart. So Maybe that little pieces includes that He can Feel Aqua.

 

After he saw Aqua's armor he felt it belong to A friend ( He dont'say ''Aqua'' he say Friend''

 

What he said.

Xemnas is the shared Nobody of Terra and Xehanort and as such has access to all the memories and abilities of both of them.

There appear to be different ratios of Terra to Xehanort in Ansem and Xemnas. Ansem SoD seems to maintain Terra's connection with Riku, for example, while Xemnas actively searched for Ventus and Aqua. 

It feels to me like a plot point related to Terra's continued existence, most likely a weakness that will be exploited in KH3 in some way

I have always thought that both the heartless and the nobody had different traits from their original incarnations. Ansem would have inherited Xehanort´s interest in science and darkness and Xemnas would have inherited part of Terra´s will, at least unconsciously. I the end, both followed the path that Apprendice Xehanort chose and ended helping their other selfs. That makes Xemnas a more tragic character in my opinion.