Is there a way of somebody going out with a gps unit and recording a trail and then transferring that trail onto x amount of other units for people that dont know the exact route to follow??

The route will be in Nepal if that makes any difference, and I dont think any digital mapping of the area exists?

Thanks and please excuse me if this is a numpty question!!!

So long as the GPS units in question can connect to a PC, then yes. Just extract the track from the one GPS and then transfer to the others.

Yes, you don't need any mapping to record a track & then to re use that track on another GPS device.

If there is no "backing" map though what will they have to follow apart from a line??

You dont really need a base map. As you follow the route as long as the line your plotting stays on top of the recorded one you know your going in the right direction.