I don’t know that I’d be interested in having sleeping/eating/drinking added into the game, maybe sleeping could add something besides frustration but the other two would just end up being annoyances imo.
I would like to see a life support module that can only be off for like an hour or two before death. That could make for some intense in-game situations. I also would like to see a fuel element added to the game so you can’t just keep going forever without stopping.
I don’t mind the speed limits. I think we all know that that it isn’t how space ships would actually move, but if they moved correctly I think it would break the whole submarine warfare element.
I would like to see more speed differentiation ship to ship, so there is more of a range of speeds than 1.1-1.3Gm. Or change it so your main drive controls your max possible speed, and your overall weight determines maneuverability and lowers your max speed, and ship types just give you different weight and numbers of module/pod slots. That way you have to balance whether you want more speed/maneuverability or more modules, for example a 2 tube weapon system would be significantly lighter than an 8 tube, but then you have ammo constraints. A ceres with the biggest engine, few modules and no cargo should be fastest, since it is the smallest ship. I could go on, but this is already way longer than I intended.