I would totally ignore the little Jack when coming in the door.

After a few moments then, drop down to his level and speak to him in a calm soothing tone holding his face. He will learn that being calm is acceptable.

My Pug wags her whole rear when she wags her tail. That makes the bladder release. So I would hold her rear down while I held her little face with the other hand. She has learned to control her bladder.

I have 3 dogs and they all battle for their "special" place. I think if you simply keep your bedroom door closed that the dog will know that the "bed" is not his.

Easy for me to say, as all 3 of my Dogs sleep with me at night.

If your dog is growling at you, ever, he is asserting his dominance over you, or is trying to. You have to, MUST, stop him from doing this. Someone needs to put on some pot holders if necessary and remove him from the bed, tell him NO very loudly in his face, and make sure he doesn't get on again. Any time he gets on the bed, pot holders out, removal and loud NO! until he realizes you guys run the house not him. Stand there and dominate the situation till he backs off.

A few times of this, and he should stop getting on the bed and maybe will stop piddling as well because they get calmer when they know they don't have to dominate the pack, as you will have assumed the dominant position with the above behavior.

"First, he piddles when excited...especially when my husband comes home."

This sounds like submissive urination. Reprimands will just get you more pee because he's signaling that he defers to you. Go to this site:
http://www.diamondsintheruff.com/
Click on FAQs on the left bar, then scroll down to 'Dog Speak' and select 'Leaky Greetings' for tips. A lot of improvement will come from the dog gaining confidence in himself and in you and your husband as benevolent leaders.

"Second, when sleeping on the bed, he growls and becomes aggressive if disturbed. So we no longer allow him on the bed with us, but it still happens if we try to make him get off if he's already been there. He has never bitten us but looks as though he's ready for a major fight!

You're right on the 'no bed' privileges. But growling is actually good - He's communicating to you instead of moving directly to the bite, so don't discourage the growling. Discourage the behavior which leads up to it: Getting on the bed. Teach him 'off' by showing him a cookie, then say 'off' and toss it on the floor. Practice a lot. But know that he's too young to have furniture privileges. He needs to EARN those over time. One of my dogs will never have furniture privileges because she's innately bossy and I won't set her up to fail. She is used to and very happy with dog beds. But if you want the dog to eventually have furniture priveleges teach him to get up only when you invite him, and to get 'off' when you want him too.

Thanks for the great link Cynthia. Our pup has submissive peeing at her puppy classes with two of the other dogs in the class and at the vets, but no other times. She is my 8th dog in over 5 decades and I have never had this problem before. I guess this one is just pay back for all the easy puppies I have trained over the years.