To get other civilizations to trade their maps without giving away too much or goig to war there are two tricks i use alot. 1. build the wonder marco Polo before anyone else and use that to contact other nations, that way they dont feel threatened by you being on their doorstep. 2. and much more sneaky send a trade caravan throughout a uncooperative nations territory to explore or a diplomat.(diplomats do get expelled if you are anywhere close to their territory).

. Might as well nab 10,000 gold too and walk away knowing that you have done no wrong
. As to "cheating because the ai cheats"... u have to realize what a pathetically weak enemy it is and let them cheat all they want if it makes the game more interesting. The only way i have found to create a challenge vs. ai (misnomered "deity level" which implies "God-like" difficulty) is to limit myself to one city.