I'm very sorry to hear that your dog has such a bad temper!
I have my Westy for almost a year now and she never has biten or even tried to. The worst thing she does is sometimes barking but as soon as I say "Hoy" wich is her word to stop. She stops (sometimes )imediatly!
They are, as I read somewhere, a small dog with a Great Dane inside! You must show him who's the boss.
The best punishment is not looking at him. pretend you don't care about him. For my Westie, that works very good.
I have a pet shop in Portugal and my Westie goes there everyday with me. She's the Welcoming party of the shop asking for petting and licking everybody. I have people that goes there everyday just to say "hello" to Wendy!
When I started to hear stories about bad tempered Westie, I was very surprised!
Hope you can figure out how to stop his bitting habit. He seems a very nervous dog.