Welcome to PPG!
You'll have several dreams in ToB, and you have Xan's journal, so it's not completely over.
And, yes, there are various conversations about Xan's death: Anomen, Jaheira, Keldorn, Imoen, Sarevok in ToB - they all speak of him. If you like Valygar, take him along in ToB - you'll have an entirely new romantically colored friendship with him(around 10 dialogues), heavily centered on Xan.
As for mod NPCs, it's difficult, because it often involves two authors, and some authors are no longer available. That's why. But if you install Crossmod Banter Pack from G3, you'll have some conversations between Xan and Kivan(if Xan is alive), Kivan and Solaufein, etc.
Glad you liked the mod, and I hope you'll enjoy ToB.