I just finished the game and would like to give my fresh opinion.
-Would you want BG4 to have a save import feature from BG3, like the original Baldur's Gate games? How much of BG4 would you want to be dependent on your decisions in BG3?
Personally, I would like that very much. The mayor's past decisions should matter, and I hope to meet my BG 3 characters in BG 4. Even shortly
-What features that didn't make it into BG3 would you MOST want in BG4 that Larian could FEASIBLY implement?
I would like my own created character to be able to talk chosen dialog lines. I understand it takes a lot of effort, but that would be awesome. Now almost mute character gave me vibes from the first Dragon Age game (which is a great game).
-What features in BG3 that are necessary for that particular game would you want removed for BG4?
I hope inventory maintenance will be somehow easier to do. I played PS5 and it was (as you can imagine) a time-consuming and boring thing to do, but necessary.
-What is your dream feature or addition to BG4 that didn't make it in BG3?
After something major happened I always took a "comment tour" and talked to every companion. Most of the time all of them had a comment about the situation, but not always. I'm not sure if there is a bug (PS5 version still has a lot of them).
Also, I like to have sarcastic dialog options. In my play through I sometimes selected the dialog option which was "tactical" because I tried to avoid instant combat (I like to explore a little first and get a top of the situation) and some of my companions disapproved of my choices and I didn't have a opportunity to explain myself. I hope you get what I mean

-What parts of BG3 are so good that they MUST be included in a potential BG4?
I liked the cutscenes, original characters, and morally hard decision-making. Also wide range of romantic options was an awesome thing! And I hope the next game has at least that wide options.
-Any other thoughts on BG4, especially as we get closer to BG3's release?
Dragonborns. I was confused because I hadn't met any of them before Act 3. I hope the next game gives that race more "screentime" and the Dragonborn companion would be an incredible thing to have!