1) tbh I have no idea how this conversation would take place... through what super convoluted method this series would explain... hearts connect weirdly and the ability to have characters in different world's converse with another or within themselves varies from encounter to encounter (I.e. kairi/ Roxas kh2, Mickey and riku Com, mickey and sora kh1, sora and kairi kh1, etc).
By the way Ansems guardian grabs Aqua (and Ven) some physical form of xehonort must exist there in that time (not necessarily in the same realm) thus it could just be time travel Ansem who is talking to Xemnas in the chamber of repose.
The entire reason I made this topic was because canonically in 2fm the chamber of awakening is first mentioned and 0.2 would be the first time is would be mentioned chronologically iirc (if the do say it in bbs my bad, but never by a form of xehornort). This is why I wondered if there had been a confirmed statement about the 2fm scene with xigbar and Aqua's scene with Terra in 0.2
2) oh ffs lol of course he still has it. I'm just not sure which version of him would. My assumption was Xemnas given that it's technically whats let of terranorts body. (BTW the ffs wasn't towards you but Nomura and his stupid symbolic key chains that will be used as a keyblade. $100 bet that Sora gets all 3 Wayfinders combined to be a Keychain for a keyblade he gets in kh3. Probably named the Wayfinder or something about friendship and the hearts of the cards).
3) I'm to lazy to do the calculations right now but given how 358 gives the exact date of when zexion leaves for castle oblivion. Knowing the exact time that Sora defeats ansem. When Xemnas visits sora... We're actually informed the general time of when the conversaion occurs. (But for the sake of being thorough I will edit this post with those dates once I have access to a computer)
Edit: Ok I did research and come up with this...
0/Start= Aqua enters the relm of Darkness (10yrs pass) Ven is sleeping in castle oblivion
Day ???= Zexion and Xigbar conversation... key note as to no date: the org has only 11 members Marluxia just joined, missing Larxene (no idea of the time gap between when she and Roxas join)/ Caslte oblivion is mentioned as the "new facility"
Day 1 = Roxas "born" / Sora is in hollow bastion/ Aqua during the events of 0.2
Day 6= Sora fights a Xemnas at Hollow Bastion/ Xemnas tells Roxas he went to see Sora (Ultimania info)
Day 7= Xion is first introduced (comes important later)
Day 16-22 = "The plan to use Sora in Castle Oblivion is established. Around this time Sora fights the seeker of darkness, Ansem, and saves the world, and Riku and the King are left in the world of Darkness" (Ultimania translation)/ Aqua and Mickey help close the door (same span of time)
Day 22/23= Zexion leave to go to castle oblivion/ Sora has not yet entered castle oblivion (as per zexion secret report on day 24)
So from rewatching the cutscence with Zexion and Xigbar... Vexen is looking for Xemnas saying its urgent. Making an asummption but I think about the Replica program (like Vexen EVER talks about anything else ever)/ in the cutscene with Aqua and Terra, he says "he's using me so that you'll tell THEM where you hid Ven". So by looking at all the dates we have that are CONFIRMED. Terranort needed the confirmation that Ven was indeed in the chamber of waking which Aqua confirms for him. We still dont know how many "days" Aqua was in the realm of darkness from her perspective. We know that Aqua talks to Terra before Sora seals the door (obv) and that Roxas isnt born yet. I think its safe to assume that Sora hasn't even been to hollow bastion yet as Roxas isnt even born.
SO all together Xigbar could not have know that Xemnas' other "friend" was in the chamber of waking UNTIL Terranort has the confirmation from Aqua that Ven is indeed there.... Thus Xemnas wouldn't start looking for Ven until he knew if he was in castle oblivion or not. And I actually think through all the convoluted mess Ive made of this forum thats the best supporting evidence I can find.