I am going to guess/speculate here as my programing skill is minimal at best.
Adding adjusting zoom level by mouse wheel is doable the rest is in your dreams & dont fully understand or maybe I am old school
Scale is 50m a hex you are not going to get a lot of detail at that level & changing that or how it works pretty much means a new game.
Think about it lets add a new terrain type, brush would be nice lets do the easy bit.
Replace say one of the pavements with it as have 3 types & use is fairly rare, define its properties & do some graphics for the file simples. Now the fun starts map generator has to know how & when to use it for the hundreds of permetations of battles you can create, AI probably has to have an idea about it to etc.
Thats just one terrain type not changing the whole shebang.
On your comment about find it hard to distinguish stuff really??
Terrain - I would describe the graphics as crisp & clear as opposed to washy, this makes recognising terrain easy on the whole.
Possible exceptions being complicated rolling ground with features might need to mouse over & verify a slope & buildings if you really want to know if they are stone or wood. Some are obvious others arent & this pretty much shows the more variety the harder it is to recognise stuff.
Units - As they are based on what they look like dont really understand this I have little trouble distinguishing diffrent units with the exeption of some vehicles which are the same but mount diffrent armament. In some cases they have a slighly diffrent camo which helps distinguish but in others like armed halftracks I either have to zoom in to see the gun or take the quick option & mouse over. I play most of the game at mid zoom levels by the way & stuff is clear enough to me.
The game is modifiable by you if you want to say change the camo on a vehicle so it stands out you can if you are willing to spend the time which raises another point.
The game you mentioned or any modern game for that fact how many units does it include, the answer will be a fraction of those included in this game.
I think most people would love to see a modern update but this is a vast game cant ever see anybody doing something on this scale again. Where we perhaps differ is I am not really fussed about the graphics unless you really are talking old schooI I want the game system updated, better arty routines etc.
On the widscreen thing I play in it & it works fine there is a sticky on this forum with the patch.