How To Train My Australian Shepherd Pup?

I have a Australian Shepherd named Teddy (short for Teddy-Bear) that misbehaves very badly,I personally think this is surprising because Shepherds are very good dogs and we have not taught him to be like this or anything.He drinks out of the toilet,chews on the cats like they are toys,chews up furniture,and barks at the neighbors.I can see why he barks at the neighbors though because they poisoned him...He also barks at every small thing he hears and he lays on the vent,and he knocks over the trash...How can i fix these issues?!??