Appearance stuff is always welcomed. I've played a little further than I had when I first posted now. I certainly notice that the characters have portraits but they are really only used for a moment when you meet them. It would be nice to have a little "Face window" when their turn comes up or something, just so you know who you're looking at. Also, for story based things that perhaps could come sooner than later, I'm thinking a short story interlude between zones. Like, you get done with the scrappers and they tell you that the Rust buckets may have the data you need to set a course for the next area or something you need, and thus you have the reason you're moving on.
Further, there seems to be some sort of flooded world thing going on (at least I think? We always seem to be getting on our missions from a sub) which I think is pretty neat and would love to hear it expanded upon, how did this happen and why sort of stuff. The world is just as much a character as any other. For that matter, if it is a water filled world, a mission between zones where enemy pirates attack and you have to fight them off would be pretty interesting.
When it comes to the idea of character creation, one thing to really consider is if you want it to be more like XCOM, Xenonaughts, or others like it, where you get characters and create them from the ground up, or if you want it to be more like Hard West, or Fire emblem, something where the characters you get are set and you only really choose how they grow. the former allows the player to make their soldiers into whoever they want them to be. In my copy of xcom 2 I'm running characters from Left 4 Dead, Payday 2, and other random people just because the idea of them fighting aliens makes me giggle.
The advantage of having a set cast however is that you can have them have a much more cohesive narrative around them, you get to decide how they interact with the other units and have more control over their story and can, in theory, use that to make the story sound more solid.
My personal advice is to pick one direction or the other and go in on it hard, because if you try to do both at once, you're much more likely to capture the worst parts of both of these elements rather than the best.
Certainly looking forward to seeing where this goes.