No ,instead,a new XmlReader/XmlWriter API is offered.like sax it is stream-based but it uses a 'pull' model rather than SAX's 'push' model.

Yes, in addition to XDR and XSD schema validation, .NET continues to support the DTD to validate the XML documents. The System.Xml namespace contains a class named XmlValidatingReader that can be used to validate the XML documents.