
Hiya,
I would recommend you get several books - Gwen Bailey has written a good one about "The Rescue Dog", and a specialist Breed book would be helpful. Border Collies aren't the easiest of breeds, and he is also at the 'teenage' stage which is difficult with any dog! (Is he show-bred or working-bred?) Add to that all the upheaval he's had in his life so far, and it's not surprising he isn't settled.
Good luck - I'm sure the books will help, and if you work hard with him it'll pay dividends and you'll have a lovely dog in the end.
:)