I think I might have a simple answer about your Google maps thing.This is just off the top of my head though, so if anyone knows the specifics, feel free to correct me. There are two methods google maps uses to find your location. First is by GPS, and this was likly used when it gave the accurate location. The second is cellular network triangulation. This is used when it can't get a GPS signal or you have GPS off (as part of your power saving scheme). network triangulation uses signal strength to judge relative distance from 2-3 points(cell towers) to find your location. The thing is, if phone is only locked onto 1 tower, it will give your location as that tower. Or if it only has two, it will guess a distant in-between the two.
So yea, unless it can use wi-fi to find your location somehow, I cant see it having anything to do at all with your router's firmware. If anything maybe your router was interfering with the GPS signal which was making it resort to the less accurate triangulation, but even that is a stretch. I think it is more likely just to be a coincidence. Sorry you got hacked though. Good luck.