Bulk shared GPS waypoint collection with routing

I am setting up a system for several employees (about 8), all armed with iPhones, to go out into rural areas and collect points of interest. We work for an agricultural company so these points will be out in fields, potentially several hundred yards from a public road. We will be collecting somewhere between 500 and 1000 GPS points, each with a name representing the field in which they are located. I want to collect all the GPS points from each of the employees, compile them into a master list, then send that list to any iPhone that needs the points. There are good solutions with which to do this like MotionX GPS, except that I want an employee to get turn-by-turn spoken driving directions from the phone, so they can safely drive to these points. This also means, they need an address to drive to, but they also need the original GPS point in the field so they can navigate dirt roads or field rows manually to get to the originally recorded GPS point.