WC3 Errors and Google/ Yahoo “Issues”

Ok, so I feel like I’m in waaay over my head at this point, because…well, as soon as I transferred my blog to a domain, I’ve had nothing but problems, leading to attempts at a solution, which seem to lead me to (yes) even more problems.

My basic issue is this: I know that my site has been validated by Google, but for some reason Yahoo doesn’t seem to know it exists. However, I cannot actually enter my URL into either one of these search engines, and get my site back as a result. Bing knows it’s there—I even come up as the third entry for some of my key terms. But I’ve had a sitemap built for a week, on Google, and nothing. I also read somewhere that if Google doesn’t at least post your site from a direct search of the URL, it means it’s been flagged or removed for some reason.
So! I got into the WC3 site checking tools, and I have, like, 100+ errors, the most troubling of which tells me that there is “No Character encoding declared at document level”. I don’t really know what this means, except that it has something to do with the meta tag? or the UT-8 encoding? I donno…but I’m starting to get extremely frustrated with this whole thing, and wonder if having a URL is supposed to be this technically difficult or profound. Can anyone please help me with this? Is there a program I am not yet aware of, that might tidy my errors for me? I’m not being lazy, I’ve just met with utter failure so far, trying to do it myself…

Thanks!