I can't really add anything to ParNone's suggestions - they are excellent. Remember to make the backyard the bestest place in the world to be. How about a big marrow bone? - or something else equally yummy. Remember only the best stuff for outside.

As far as his fear because of the fireworks - again just like Par says - make sure you are not telegraphing your anxiety to him. Think "happy - happy - joy - joy - we are outside having fun". When Leo gets fearful, I just tell him (think squeaky little girl voice) "Leo - what a silly silly doggie - lets play" Dogs have great memories - it is important that you replace the fearful ones with some happy ones.

Good Luck