Dauschund/poodle mix 1 and a half,need help?

he will not potty train, he is aggressive,and possessive especially around me even towards other family,he has a killing(animals) and biting issue with people, formal training did not work, they suggested he be put down,suggested it may be a problem of the mix, has anybody else had this problem? Does anyone have any suggestions? He also eats everything in sight ie; wood, drywall,denim,paper,plastic,metal,he ate through his own crate....for pete's sake!!!He has started to attack my other dogs if he thinks we are going to give them any attention. We don't want to put him down but don't know what to do, he is having a serious affect on the humans and other animals in our house.