I generally don't bother much with the map on the hud except for getting oriented with direction, generally if I actually need to look at a map, I go with the map in the main menu.
I can't comment on your second question as I don't use Morrowind enhanced.
As to Morrowind Comes Alive, my main complaints with it have already been stated, some of the new NPCs that attack you are quite difficult for low level characters, also, it seems to occassionally allow them to spawn in towns as well, which kind of annoys me as outside of quests which require you to kill someone who is inside a town, I generally regard them as places that should be relatively safe. Nonetheless, I'd recommend it.
About mods that expand locations, I think it depends a lot on which ones you get, usually, they probably won't have much of an impact on game balance, seeing as they don't alter game mechanics and if they do add any new items, these usually aren't the main focus of them. I think the main problems you could get with that kind of mods are, for one thing, conflicts, since these mods need to add new objects to towns, if you have other mods that also add things to those towns, this can cause issues, usually ones that result from both mods placing items in the same location. If you get a mod that expands Balmora, for example, and also download a mod that adds a new building to the Balmora area, and the latter mod happens to place the building in a location occupied by something from the Balmora expansion mod, you might get things like one building stuck inside another, or if one or more of the mods involved makes changes to the landscape, you might see buildings with their doors blocked by pieces of the landscape, gaps in the landscape that allow you to see the void and water beneath, and other such unpleasantness. Also, these mods could potentially result in performance issues, Morrowind is not the most optimized game ever made (Which is, of course, a huge understatement.) and if there are a lot of objects on screen, it can perform poorly on less powerful systems, especially if you have lots of graphics mods installed, mods like this can dramatically increase the amount of objects rendered on screen at one time due to adding buildings and other such things to towns, which may potentially make the game run poorly. This doesn't mean you shouldn't use them, of course, just that these things should be taken into account. If you are going to use such a mod, it would be best to be careful about using other mods that add things to the locations it alters.
This is a REAL problem. I have noticed (on the net) that Morrowind is unbalanced cause makes the Pg become a Semi-god quite early. I have Morrowind Enhanced but I don't know how to set it in a way it will be balanced all game long
The general idea with balancing mods, at least one of them, is to make it harder for the player character to become over powered, which is indeed a problem you encounter in Morrowind. At the start, the game can actually be fairly difficult as you're character isn't very powerful, you'll probably die a lot if you're not careful where you go, and will be missing a lot in combat, but at later levels, most enemies will become very easy. I doubt it's really possible to completely avoid that problem without adding in enemies that are challenging even at really high levels, but with the proper balancing mods, you should be able to make that happen much later.