Book I have read recently

Beginning XML, 5th Edition

is the book I have read recently. It is a good introduction to XML and related technologies. It is not a reference book, but a textbook or tutorial. 

It tells you about XML, namespaces, XML Schema, XPath, XSLT and among interesting things - WSDL and SOAP. This book is a good start to learn XML.

Among XML editors I recommend to use Altova XML Spy. You can download trial version. 

In java you can use IBM java api for XML which provides support for XML standards XSLT 2.0, XPath 2.0, and XQuery 1.0. Link to the book.