I think it's arrogant to think you're 100% right about EVERYTHING. But I'm 100% sure, based on the evidence, that, say, gravity is real. I don't think that's arrogant, I think it's realistic. If evidence came up later to refute it, I would reevaluate my position. I think you can be 100% certain of something and still be willing to change your mind if, later on, additional evidence presents itself.
Based on the evidence available to me, my answers to your questions are:
* JW's not 'God's' true organization: 100% sure
* Bible not inspired: 100% sure
* A personal god does not exist: 100% sure
* No god-like creator exists: Hm. Probably 99% sure.
I'm an agnostic atheist. My boyfriend, meanwhile, you might call a spiritual agnostic. He feels in his gut that there's SOMETHING out there, maybe some sort of higher power or force or whatnot, though nothing like the Christian god definitely, perhaps something less benevolent (or tyrannical, depending on your perception) and conscious, but rather more neutral or maybe a removed observer. I think he leans more towards Buddhist-type feelings on the subject. I, on the other hand, feel no such connection or mystic/supernatural force at all, and never have, even while a JW, but don't wish to invalidate a feeling which clearly gives him comfort. If, down the road, scientific evidence (not anecdotal evidence) came to light in support of a god-like creator's existence, I'd be willing to revisit that opinion and revise it. I don't think that my current absolute or near-absolute certainty makes me arrogant, ignorant, or prideful. Just confident in my current opinion based upon the research and evidence I've seen presented by credible and impartial sources.