I like a button on the UI that lets you select which ammunition you are using - it shows what you have in your quiver with little radio buttons to show which type is active. It makes sense to have a quiver on the character model, but I'm not going to be too upset if that doesn't happen. I can imagine it being there and that's fine for me.
That said, this draws me back to the "if everything is special, nothing is special thing". I tend to be very against most of the consumables that Larian has created - strongly dislike the abundance of elemental arrows (among other things) that are available from the get-go. I would love for them to be gone.
From a PnP perspective, I find it's very rare to see +1 weapons at all before level 5 or so. I'm all for adding +X ammunition and having them be selectable from the quiver instead of normal arrows, but you ideally wouldn't see them within the scope of the EA. This is fine. I like spending the first few levels getting to know my characters skills without all sorts of magical enhancements. Then as you notice the enemies starting to ramp up, a few magical items start showing up to give you that little bit of edge that you need; this makes them feel really special and you have to pick your moments when to use them (with consumables, like arrows and bolts, at least). If you just have magical arrows right away without feeling a little bit of a desperate need for them, it devalues them - makes them seem less cool.
So, I'd love to see all of the existing fancy arrows removed from the game entirely. Have the players find a few walloping arrows/bolts somewhere in the scope of the EA. Maybe there's a vendor that has a few to sell or you find a cache of them hidden somewhere. They're rare, and they might not work (you might miss and there's a save involved), but if you can land that perfect shot at just the right moment against an enemy that you absolutely need to knock down, it's going to feel incredible! Then start introducing +1 ammo (still rare) in the second part of act 1.
This shifts the focus from "check out all of this powerful ammo I just got" to "check out these amazing things that my character can do", and the fancy ammo is there for you when you need a bit of an edge. If you want you skillset to be about being an elemental archer, include that as a subclass in the game (it already exists in 5e).
