Unable to Determine Parse Mode!

The validator can process documents either as XML (for document types such as XHTML, SVG, etc.) or SGML (for HTML 4.01 and prior versions). For this document, the information available was not sufficient to determine the parsing mode unambiguously, because:

the MIME Media Type (text/html) can be used for XML or SGML document types
the Document Type (-//W3C//DTD HTML+RDFa 1.1//EN) is not in the validator's catalog
No XML declaration (e.g <?xml version="1.0"?>) could be found at the beginning of the document.
No XML namespace (e.g ) could be found at the root of the document.

As a default, the validator is falling back to SGML mode.

Info No Character encoding declared at document level

No character encoding information was found within the document, either in an HTML meta element or an XML declaration. It is often recommended to declare the character encoding in the document itself, especially if there is a chance that the document will be read from or saved to disk, CD, etc.

See this tutorial on character encoding for techniques and explanations.