Welcome to the Git version control system! Here we will briefly introduce you to Git usage based on your current Subversion knowledge. You will need the latest Git installed; There is also a potentially useful tutorial in the Git documentation.
PyFacebook is currently best-tested with Django, and if you are just starting out with Python web development, the author highly recommends this combination :-). If you'd rather use another framework, there are also Pylons and other WSGI helpers in PyFacebook as well.
XPath is used to navigate through elements and attributes in an XML document. XPath is a major element in W3C's XSLT standard - and XQuery and XPointer are both built on XPath expressions.