Across the board... HELP!

My dog's name is Rusty. He is 5 1/2 months old. I have had him since he was 5 weeks old. He has behavior problems that stretch across the board. I will try to briefly describe each of them, and would very much appreciate any help I can get with any or all of them.

1. Crate - I am a college student so I have class every day for about 2 hours at a time. He is NEVER in his crate for more than 2 1/2 hours. I always let him potty right beforehand, give him plenty to do inside the crate (kong, nylabone, and a toy or two), and I let him potty as soon as I get back while somewhat ignoring him for 5 or so minutes so I don't overexcite him. STILL, my roommates tell me that he is yelping and barkign and screaming the ENTIRE time I'm gone. In addition to this, he is apparently throwing himself against the side of the cage. I've tried covering it with a blanket, which he pulled into the crate and shredded it. I put his little bed in there and he shreds it. This has been going on for 2 months, daily. I've even put him in there while i'm home and he just whimpers. I leave for 5 minutes at a time and he just never stops crying.

2. Peeing - whenever he meets new people and they pet him, he loses all control of his bladder. When I come home from class, if I pet him and he's excited, uncontrolled pissing. Meeting a new dog, piss. He's not even aware of it, its just happening. He'll even submiss to someone petting him and piss all over himself. This is really annoying - is there any way to stop it? I'm tired of having to take him outside to greet anyone who comes over.

3. Potty training - He's 5 1/2 months old and is still VERY inconsistent with potty training. He has NEVER gone to the door to tell me he has to go potty. He keeps having accidents, granted they are less frequent than when he was 5 weeks old, but I just want to trust him and I can't because of the accidents. When I catch him doing it, I frimly say "Rusty, NO!" and immediately lead him to the door. I then say "go potty!" until he goes and then I shower him with praise for peeing in the right spot. I have been 100% consistent with this since I got him. I don't know what else to do!

There's more but I'll stop there for now. The main ones are the crate and the potty training. He never pees or poops in the crate so I have that going for me, but the crying is making my roommates hate me. And I feel bad for him being that miserable for 2 hours everyday. If I could just get him potty trained, I wouldn't even have to worry about the crate - which he has never liked. No matter how much I treat him and praise him and coax him, he has never liked that crate.