I think you have been givne some great advice here :)
I have been involved with a farm bred BC and I can tell you he gave his owners some headaches!!! At the end of the day the best thing they did was to "work" with him every day. They did this by throwing a stick (sticks are not ideal as they can be dangerous; a Kong would be better) into light cover (bracken or long grass) and then directing him to it.
They used phrases like "this way" "that way" "on on on " and "back" and lots of arm and body pointing. In this way, it was better than basic retrieving as he was using his brain every day and it was just what he needed, plus the fulfilment of working with his owner.
Have you got the excellent book "Understanding the Border collie" by Carol Price. Do read it, it is very good and helpful.
As for the being scared of men - the key is to let her approach them, and for them to pretty much ignore her until she is very happy with them. If you have men who can help, get them to throw titibits on the ground (not AT her

) and over time she will learnt to approach them.You may need to actively set up a training programme where you can set up this scene every day or so. But take it slowly and let her decide when she is ready, or it will get worse if she is forced to accept them approaching her. Her barking and snarling is basicllysaying she is scared and she would probablyl bite if backed too much into a corner :(
LIke the others, I feel the key is more mental and physical exercise here :) Good luck with her.
Lindsay