IMO you DEFINATELY need to get a behaviourist in.

Your lad should never bite or snap, and food guarding/aggression is a sign of issues as well as being an issue in itself.

I'm sure he's a lovely dog, but he is suffering potentially dangerous behaviour issues and it is always best to nip these things in the bud.

For now, the advice I can give you is to not force him to accept strangers. Loads of praise when he approaches or looks but doesn't bark/growl but NEVER force him to accept attention from people, or sharply reprimand him for fear or aggressive behaviour.

Ask people NOT to reach out to him, even if he does come over to sniff, also ask them not to stare him in the eye or 'squeal' in a high pitched voice at him.

Sometimes, people are so desperate for your dog to like them that they will not listen to your request to allow him to come around - Be careful that you place yourself between him and the people so that he feels 'safe' and repeat your request that they do not attempt to force themselves on him.

This is the advice I recieved from my behaviourist with regards to the stranger behaviour, and I would recommend you follow it in the meantime but I would really think you should get your own behaviourist in soon!

HTH

*ps remember loads of praise for any 'good' or 'non aggressive' behaviour.

Toni



* sorry, forgot this bit
At night, he'll jump and start barking rather defensively at even the smaller noises or suspicious things.
If you can, try to completely ignore this behaviour. Don't shout to be quiet, or give him attention for it at all... Eventually, he should realise that all these things are normal, because the 'pack leaders' aren't worried about them... leading by example, you know?

Also, as usual, any 'new' behaviour or physical symptom would be a reason to have a vet check-up, as there can sometimes be physical reasons for anxiousness or aggression.