looking good so far.
I would keep it 4km, ye 2km has more detail in the terrain etc but for the most point, you do not need that detail, only when it comes to urban maps etc do you really need it for different levels of terrain in the city etc, for mostly open ground and village like this map, 4km is fine, you just need to watch out for the terrain LODs as they are the worst bit.
Gameplay wise of 4km with INS, you can focus the gameplay into areas, you can either do this with combat zones, or just focus objectives into areas of the map (best IMO). Think kinda like dragon valley, has all its objectives up the valley, you can do the same thing here more or less but not in the same cq wack a mole game mode and with just ammo caches in these areas, with maybe the very slight chance of a ammo cache being in the mountains or w/e to keep each round interesting

Providing there is transport choppers for the Brits, and lots of ground transport for the ins (techinals, cars etc), should be fine
as for your pics, your dam is starting to take shape but needs more detail, mainly texture detail, give it some dirt and crack textures will really spice up the texture and make it look less repetitive and more unique all over, with adding detail to the cranes etc, and maybe the odd bit of concrete chipped away will really refine it.
What I'm mostly concerned about is your villages, mostly because it looks like a cluster f*ck of statics from what I can see but also that 90% of thous objects are destructible, this meaning that if you have too many destructible objects on your map you will increase the chance of going over the netwrokable limit on the map and then result in the server running the map crashing all the time, think of Op Archer and Al Basrah in .7 or was it .75? Spread out your buildings, give them compounds, swap out the dest versions of the Afghan statics for my non dest Afghan statics that are in .8 and not only will you make it look overall nicer, you will increase the performance on your map since the more statics you have, the more meshes are loaded, the more texture memory is used and the more lightmaps are needed for them all which all in all result in lower performance. As IronTaxi always says, "less is more", aim for filling up areas with small props like pots, rugs, small rocks and bits of grass on the ground, this will add to the overall detail of the map and will make everything look so much nicer rather than filling up areas with just pure buildings.
Hope that helps, keep it up
