1. This is really more Agnosticism.
Eh. I've been reading sciforums for maybe three or four years now (and I actively participated for about two years - Hi Q!!) and I can't tell you how many times this 'debate' has come up. So here, though I'm a little out of practice, is how I remember it going...
[cough cough]
Okay, atheism is, technically "without theism". That is, it means non-theistic, having no god-related beliefs.
Agnosticism is this crazy little arguement certain philosophers (and I use the term loosely) and others have adopted to try and distance themselves from a third category.
That is, the category of people who genuinly hold the arguement "there is no god, there definitely is no god". I don't know what the right thing to call these people is, but it ain't atheism.
Now, within the agnostic tribe there is certainly a split (if not many). Some will pose the arguement "well, I just don't see any proof of god, so I have no belief". These people, while identifying themselves as agnostic, seem more suited to what atheism always was and generally is considered among philosophers and theologians. But hey, whatever floats your boat. Then, there are the agnostics that better fit the term. The ones who say "well, there's no proof either way".
It is with this type of agnostic that an atheist generally marks his split. There's no proof a giant invisible manta ray doesn't live underneath mars. That doesn't mean I'm going to adopt some weird ass agnosticism towards manta rays underneath mars. Essentially, saying "there's no proof it's
not true" (which, firstly, being a very flawed arguement to begin with) opens the door to forcing one into taking an "agnostic" stance towards every single possible thing that hasn't been disproven.
I give no credibility to the claim of the existence of god (in any modern sense) any more than I do to the claim of the existence of Ra the Sun God or Sasquatch the Bigfoot. Lots of people have thought or think they exist, but that doesn't mean a damn thing. Human beings spent most of their early lives attributing every possible natural phenomenon to a higher being. It's the old quote: "If god didn't exist, it would have been necessary for us to invent him".
To return to the original point full circle:
Saying "There's no proof for x, therefore I don't believe in x" means your agnostic towards x (as Prince James is doing) means that you must be agnostic towards a literal N number of possibilities. And that's just silly.