I am really happy to see that Warhorse Studios is embracing mods and talking about it right from the start! Props to them because when I first heard of this game my first thought was "Well that looks awesome but with no mods Skyrim will always beat this game." IMO. So Warhorse, you gave me exactly what I wanted before I even backed the game!
For mods that I want, graphic overhauls. Yes I've never seen the game live so I have no idea how good the textures will look but if you could use something like ENBs from Skyrim I would be incredibly happy. They really do change the overall vibe of the game. Another thing that would go great along with that is immersion mods like weather mods such as (again from Skyrim, sorry for that) Climates of Tamriel.
This might be a hard game to keep lore friendly because it is not fantasy. I hope people try to keep somewhat lore friendly mods to keep this game from becoming "another Skyrim". Sure I want some fun in the mix to that isn't lore friendly but this is a new game and I have to play it a while before I would want to change it too far from what the original developers intended. I suppose this might be something that I would want later because the game uses CryEngine and looks very good as is. For first mods I would probably want them to be character and quest related like character clothing and skins or new stories that add to the game.
Anyways I hope the modding community really embraces this game. I'm not a modder myself but I really appreciate the ones that spend hours and hours to create content that everyone can enjoy.