Recommendations on Development Resources

I am new to XML development however I want to enhance my skill set. As
a result, I am looking for recommendation for resources to accomplish
this task in the following areas:
- Books / Web Sites / Classes / Any Other Educational Material
- Free applications to process XPaths, XSLT, and etc
- Purchasable development application to process XPaths, XSLT, and etc
(Want to first go with the free stuff and then as things get more
intense eventually invest in an application which has debugging and
etc.)
- Misc. (Any other areas which I might have missed.)

Any comments would be welcomed.


Regards,


R

.