How to implement a few things for an FPS?

I apologize if this has been asked before, but I looked and couldnt find anything that could help me.

How can I implement a radar? By radar I mean something that looks like the ones in this image http://www.thegamerschallenge.com/wp-content/uploads/2012/05/Multiplayer-goldeneye-n64.jpg

Another thing I cant figure out is AI. If anyone can link me to a smart AI tutorial or something better then just adding a “track to” logic brick then it would help me out greatly.