Behaviourists' help needed please.

P.S
 
His last bad behaviour is snarling when I am at his dish.
I reward letting me near it, delivering it etc, and he has gone from snarling/full teeth showing while foaming at the mouth, to the point where he just twitches into a quick flash of the  teeth now when he is tired & feels like challenging with defiance. (3 straight years of 2x daily training to get to this point! Ugh!)
 
Does this mean the dog is stubborn and will just need to be trained for his butt biting agression for 3 full years to get him to stop biting the older dogs butt when ppl approach?? The vet calls it reverse agression. He wants to jump on the approaching ppl but the fence prohibits it, so he jumps on the older dog instead.
He learns all other things soooo quickly!
 
 

I dont know about the whole biting the other dog, but him snarling/snapping at you when u get near his dish is a BIG problem. He obviously considers himself the alpha dog and that is a big NO. Until he learns otherwise do not feed him in his bowl. Handfeeding is a great way to establish your authority.
 
Also, make him work for every little thing. If he needs to use the bathroom, make him sit/stay before taking him out. If you are going to pet him, make him sit or lay down. Even the tiniest scratch on the head requires him to obey a command. That way he will learn who is boss.
 
Sorry I cant help you with the biting of the other dog, but there are more experienced memebers, and im sure youll quickly get an answer to this!

The butt biting isn't your major problem.  Stop testing him by getting near his food bowl - this is a dog that will bite!!!!!  Instead, learn how to retrain him - best protocol I know is in Jean Donaldson's book, "Mine! A Guide to Resource Guarding in Dogs". 
This sounds like a dog who thinks he's in charge.  Patricia McConnell has a little book called "How to Be the Leader of the Pack and Have Your Dog Love You for It" - good reading. 
If you continue to have problems with the dog guarding things from you, seek help from a behaviorist.  This doesn't get better with time, you need to address it correctly, and right away.

Great advice Spiritdogs, and great booklet too.  Lots of good common sense in that tiny little book.

I'm sure I gave the wrong impression with the food bowl here. 1) I don't test the dog. I set his food, he sits till I leave, then eats. When he is tired and I bend to set his dish down, his nose teitches, and sometimes his lip curls over his teeth for a second, or half a second. The point is, he had MAJOR food bowl agression and I rid him of it all but this snotty attitude ttwitch when he is tired. I respect your concerns over the growl, snarl, foaming at the mouth, and I shared them, but he doesn't do that anymore. We've established that he is not my boss
I just mentioned it to show how long it took to break his stubborness, but it is breakable.
 
Now, he has (diagnosed) reversed agression. I am told to be absolutely 100% on top of it, given his stubborness to drop a bad behaviour in the past (his bowl guarding), and I do this too. Just wanted to know if there is a faster method known. The old dog can't show him she is boss so I have to show him for her.
She is old and fragile and doing her "job:, which I need him to do, instead of biting her butt when she shows dominance toward uninvited approaching visitors.
The pup need to know it is a team "job" to guard us, not take it as a dominance display that challenges the dog dog standing in the pack.
 
I will get the book nonetheless.
Thank you.

We've established that he is not my boss

 
The one thing you cannot do is establish which dog is higher in the pack.  That's the reason it's important that you be the undisputed leader.  If you dog can make you go away by curling his lip, he is your boss in that situation - leadership can be contextual.  If your dog is still curling a lip at you when you lower the bowl, or when you try to take it away, you need to do something.  If that were my dog, I would eliminate dinner in a bowl as soon as the lip curled.  The next night I would begin hand feeding the dog, and doing the rest of the "Mine" protocol.  When you feed by hand, the dog realizes that the food is yours and you are just sharing.
Once you are able to feed from a bowl again, ask the dog to "wait" until the food bowl hits the floor.  Any forward movement means you take the bowl up and away - dog waits, it lowers.  If the dog waits until it hits the floor, he gets to eat uninterrupted.
 

Thank you. I will hand feed his this morning and tonight and see how that goes. If not well, I will repeat till he gets it.
Thanks

My corgi attacks our min pin when the mailman comes. Very embarassing. She doesn't hurt him and I don't know how to stop this behavior. Its only the mailman so I let it go.