Hiya,
I'm new but your post caught my attention because I have an Austrailian cattledog as well, and she does not bark...the only time she feels compelled to is when we start playing and rough housing and then she'll give out a bark with a slight howl sound to it, it's [Edited for inappropriate languge, please review forum policies for more information] cute but that's it. And even then it sounds like she's forcing a bark out.
And as to the training commands - my dog doesn't ever have to be put on a leash because her loyalty and herding, packing instincts were nurtured by our training her to the point that off a leash she will never move farther away than 10, 15 feet of us, even on trails. She never wanders away. It's nothing special on our part but it was this training method called "Follow the Leader" that is very sucessfull with cattledogs. My dog- (Fox is her name) will even heel off a leash, and she has no problems with come and stay commands, but I can honestly say that having this type of breed to train made it a little easier.