What breed do you have? Most people use wethers b/c they are generally bigger and stronger than does. And does can be temperamental when they are in heat, can't use them when they are preggo, etc.
When I was a little girl, the people that boarded my goats for me had a couple of wethers trained to pull a cart. It was sooo cute!
I don't know about getting them to carry a pack. I don't think there would be much to it.
Goats make great hiking partners. I just start them out when they are young by taking them out one at a time. They don't like to be left alone, so stay with me without a leash. We stop and I let them browse and just walk away and call them and they follow.
They catch on real quick and then you can take a group of them out and they stay together.
With older goats it helps if your alpha female follows you, then everyone else will follow her, even if they aren't real people friendly. I walk mine all over and they really enjoy it, and have never run off.
The babies will follow their mom so as long as mom is friendly she will teach the babies. They are herd aniamls and it's natural for them to stay in a group.