Creating a RTS Map

I want to create a map like on AoE but I dont know how. I tried lights but they light up my terrain very weird and you can see the seems on the terrain. it also slows down gameplay, same goes with making dark planes disappear when you walk into them to discover that aria. I also want to know how I could make the aria not update when your troops are not there so you cant see what the enemy is doing all the time. here is an example.

I dont want you to write the code for me I just want to know how it can be done. Thank you.