Blacks Link and Bowen Road are *not* dog friendly in that they both have been targeted by our resident poisoner.
Having said that, we always take our dogs on both paths, but keep them under leash when we do so.

Anytime is a good time :-) I was out with the kids today and we did 10km around TaiTam park. Yes, its very hot but if you bring enough water, its not that bad; you will get used to it.
Usually, it will get cooler around Sep-Oct timeframe and when that happens, we will do much harder hikes.