If you want to keep him, you might consider preventing him from getting access to the front fence. Maybe make a second fence further back so he can't get there. I think legally you have to allow people safe access to your front door, eg the police, firemen, meter readers etc.
You may also want to consider muzzling him while you're out - to minimize the chance of him being able to do serious damage - but remember he can still hurt small dogs by stomping on them and whacking them with the muzzle.
But you really want to get some help to learn how to re-train him to be more well behaved and calmer.
I've seen these two trainers recommended for the ACT area but I don't have any personal experience with either of them. If they can't help with your specific problem, ask them to recommend someone else they respect.
Heike Hahner in Braidwood
Raelene Koerber in Canberra
Welcome to Raelene Koerber Training & TTouch
You may want to read this first for help choosing a good owner and dog trainer (and avoiding some of the bad ones).
How to Choose a Dog Trainer | Steve Courtney Dog Training