I would guess that the answer to the "How do you know when your dog accepts you as leader?" question would be something along:

When you know that your dog will do whatever you ask him, provided that he understands what you want, under any distraction.

What's still blurry in my mind is the line between leadership acknowldgement, and submission. Because, there's a difference right?

I mean, I do make a difference between "I'm going to listen to that guy because he's my boss and I respect him" and "I'm going to listen to that guy because if I don't, he's going to hit that remote and buzz my neck that's not funny".

In his podcasts and articles, Ed often mentions how you have to be "fair but firm". One one hand he tells us to show our dog that we're the best thing the world ever offered them, and on the other hand we have to show them that we won't tolerate them acting against our will.

I don't want to derail the thread with my own experience but I think this is relevant to the original question. Issues I'm having with my dog is that while I work hard to bond with him, he acts retarded whenever he gets happy/excited and I have to correct him. So I'm in a perpetual cheer/scold cycle that certainly confuses him.

My best example for this is his reactions to strangers. I've made the mistake of allowing everyone to pet him in his youth, and at the same time I was pretty much the only person in the world to ever correct him at all. The result is now that I got a dog that barks his as* off whenever he sees a stranger come because he wants to go meet them, jump on them, play with them. In his mind, they're obviously more fun than me. And if he somehow gets to them, then it's indeed party time for him (JRTs jump very high, about adult shoulders level).

Bottom line is that I'm the best thing in the world for him... as long as I'm the only thing in the world around him. He's great when we're alone, but bring in distractions and he's a total asshat... then I either have to put him away (crate) or start correcting a dog who doesn't give a damn unless it's a high level correction since he goes in "retarded" distraction level instantly. (which isn't exactly what I want to do for 20minutes when I have people come over)

Sometimes it can help to see non-success stories to learn from others mistakes. I hope this one helps you somehow, Lilianne.

I think there's a couple of key points here. The first is you have recognised the need for some improvement - and well done for that, and for asking questions!

The next thing to remember is he's only 5 1/2 months old. Still very much a puppy! He's also still teething, which will cause a lot of the mouthing behaviour.

If it were me, I'd be focussing on 3 main things.
1 - NILIF! He earns EVERYTHING. Food, fuss, treats, everything. That means being calm before getting out of the crate, sitting before food or fuss or playing etc.
2 - Go back to basics with Pack Structure and forget formal OB work for a bit. Things like going through doors first, seeing you eat first.
3 - Walks are YOUR walk, not OB training (yet). He's coming along WITH you. His first thing in the morning is out of crate, leash on and walk! Before potty, water anything. He can pee WHEN you say on the walk - don't leave it too long!

A week or 2 of this will really re-establish a bond and trust and respect with your puppy. When you have got that bond, you can start back on your OB training with markers again.
You have some good DVDs already. I'd suggest reading Cesars' "Be The Pack Leader" book too as a simplified introduction, and use this and the Leerburg methods to help guide you.

Let us know how you get on!