I dealt with separation anxiety with Cash when he was about the same age as yours - 8 months. He used to go crazy and tear up my house when I leave. Wherever I left him, it would be left in ruins.
Your dog has a trigger - the sound of your keys - just as Cash did. What I did is play with the keys while I am sitting on the couch and every time I walk by them I would pick them up quickly, jiggle them and put them back down. The doggies get tired of getting excited for nothing very quickly.
I used to put Cash in the bathroom as well. I am a student and couldn't afford a expen, crate or gate, so I got him used to the bathroom by putting him in there with his bed, his food, water, and toys. This actually didn't help. He tore up the bathroom - ripped the toilet paper to shreds, pulled down the towels, etc. So, I simply left him to roam the flat - it wasn't very big anyway
and he was fine.
I always got him some activity balls, kongs and the like, so that he wouldn't be bored when I am gone. He liked these so much that he actually looked forward to me going to the cupboard before leaving and he didn't freak out anymore.
Also try ignoring him for a few minutes before and after you leave. And if he freaks out, ignore him. This is very difficult - especially when you get home - but it helps.
Hehe, I just remembered: Cash used to pull down my pants while I was getting dressed
. As soon as I tried to put on a pair of shoes, he would run off with the other one
. Clever little bugger.
Sorry for the long post, but I hope this helps.